St Andrews Lynx

Not that I know this for a fact, but I could imagine that it's because they worry about how you might (over/mis)interpret their words. Maybe they can already imagine a situation where you get a C and come to them to complain that they promised you that you would get a B, so what happened? Followed by a petition to up your grade because a C is a very bad outcome for you. Or maybe they are just tired of talking so much about your grade and apparently not enough about your actual performance and what you are learning and are capable of doing, topics that are more appropriate for graduate students in a graduate course. Or maybe, just maybe, they aren't done grading but still took the time to skim your assignment before your deadline and give you the relevant feedback: given the fact that you failed to complete certain parts of the assignment, you are not going to pass, but your exact grade still remains to be calculated. 

Personally, I'd deal with this by not dealing with it...at least right now. 
Your friend is upset. You are upset and rather stressed. Even if you apologise to her, you still have several more months where writing is your priority and will be taking up most of your time. 
I'd send her a short message saying (i) you are sorry that she's unhappy (ii) you appreciate her as a friend and know that you've not been able to give her your full attention (iii) right now you need to focus on thesis writing until April and it is detracting from ALL your friendships, not just hers (iv) how about we do something nice/fun together in April once you have finished with the crazy thesis stuff? 
If she isn't conciliatory after your response...don't waste more time and energy on it. Focus on quality time with your supportive friends (if any of them can try and gently explain to BF about grad school stresses & time commitments it might be better than you getting sucked in). It might be that your friendship has run its course, or you have grown apart with your different life experiences...but you can deal with that after the thesis.  

If "what is the grade I earned on my paper" is the question you want to ask the professor, then ask that question. The professor isn't a mindreader. "Can it be guaranteed?" No. Nothing in school is guaranteed until you get it in writing. If you are given an assignment without a rubric, then it is up to you to do your absolute best, and spend as much time as you possibly can to do it well. If you are not confident in the way you are doing the assignments, you could hire a tutor, or you could spend more time on them. By being so frugal with information about this issue with the people who are trying to help, you present yourself as someone who is unwilling to work hard for what you earn. This may not be the case, but that is the presentation. It seems that you are still in a high school mindset, where the teacher is supposed to tell you exactly what you must do, provide rubrics so that you can work within that framework just as hard as it takes to get the grade you are aiming for on that assignment, then you regurgitate the assignment - and then you get handed a grade. That's not the way school is supposed to work, and it is not the way graduate school will work. You have to work much harder than the professor if you want to learn all you can. That's just reality. Look at the syllabus again. What are the course goals? Are you there yet in the course goals? What do you have to do to get yourself there?
If the course is not challenging, then you would have earned all the possible points on the assignments. You should re-examine your thinking on what "challenging" means.

Yeah, I quite enjoy lab meetings. Your set-up sounds like more of a slog than mine, though!
Some of the reasons I like them:
Helps me keep up to date with what my colleagues are doing. From my day-to-day interactions I know if they project is going well/bad, if they're stuck on a particular problem; but I don't really see the big picture until the present their work to everyone.  Learning from others. Sometimes my PI will give feedback about an experiment design or remind the speaker "You should always..." In which case I've saved myself from making a mistake they made, or I can improve upon my approach before I need to ask anybody for advice. Or even if someone has nicely set-up slides I can copy their formats. Motivation to do work. I tend to run more experiments in the week leading up to my turn at the meeting, simply because I want to present good data. Stepping back to see the bigger picture(s). I find that the mere act of making slides helps me make sense of my (sometimes rambling) project & side-projects. I have to think about ways to present my material in a smooth narrative and spot the gaps in my project (e.g. I want to tell my audience that X proves Y, so what control experiments should I run to strengthen my argument). Learning about new papers or ideas. We always give some background on our projects (as well as doing separate literature presentations), and it gives me exposure to different subfields that I wouldn't necessarily read up on of my own accord, but I find interesting nonetheless.  From what I've seen though, lab meetings can vary in quality. If people aren't learning from the repeated presentations and what others are doing - like, they still make messy slides meeting after meeting - or if the PI isn't moderating in a productive/critical way then it can be a slog. Having a bit of time between your presentations seemed to help my lab deliver better-quality ones (after only 2-3 weeks I didn't have that many new results to present, so my presentations became sparse and repetitive). 
Don't be afraid to suggest changes to the lab meeting format! If you can frame it as a "this will make us more productive" and have back-up from multiple lab members, you may well be able to improve on the lab meetings.

Yeah, I quite enjoy lab meetings. Your set-up sounds like more of a slog than mine, though!
Some of the reasons I like them:
Helps me keep up to date with what my colleagues are doing. From my day-to-day interactions I know if they project is going well/bad, if they're stuck on a particular problem; but I don't really see the big picture until the present their work to everyone.  Learning from others. Sometimes my PI will give feedback about an experiment design or remind the speaker "You should always..." In which case I've saved myself from making a mistake they made, or I can improve upon my approach before I need to ask anybody for advice. Or even if someone has nicely set-up slides I can copy their formats. Motivation to do work. I tend to run more experiments in the week leading up to my turn at the meeting, simply because I want to present good data. Stepping back to see the bigger picture(s). I find that the mere act of making slides helps me make sense of my (sometimes rambling) project & side-projects. I have to think about ways to present my material in a smooth narrative and spot the gaps in my project (e.g. I want to tell my audience that X proves Y, so what control experiments should I run to strengthen my argument). Learning about new papers or ideas. We always give some background on our projects (as well as doing separate literature presentations), and it gives me exposure to different subfields that I wouldn't necessarily read up on of my own accord, but I find interesting nonetheless.  From what I've seen though, lab meetings can vary in quality. If people aren't learning from the repeated presentations and what others are doing - like, they still make messy slides meeting after meeting - or if the PI isn't moderating in a productive/critical way then it can be a slog. Having a bit of time between your presentations seemed to help my lab deliver better-quality ones (after only 2-3 weeks I didn't have that many new results to present, so my presentations became sparse and repetitive). 
Don't be afraid to suggest changes to the lab meeting format! If you can frame it as a "this will make us more productive" and have back-up from multiple lab members, you may well be able to improve on the lab meetings.

There are a lot of academics out there who don't have the best social skills. There are plenty professors who can diplomatically tell a prospective student that they don't have funding/space* and think you should join another research group. But to me this sounds like a professor who doesn't really want you to join their group but isn't managing to give you an outright rejection. He's stalling for time ("go away and think about this"), bringing up multiple concerns (funding, hobbies, do you know what you're getting in to). I mean, accepting someone into a research group isn't difficult ("You want to join our lab? Great! Let's meet next week to talk about projects."). 
It's like when someone is trying to dump you: "I don't know if I want a serious relationship," is a face-saving way of saying "I don't want a serious relationship with you." Except in this case "Are you sure you want to do a PhD in my lab?" could well be a way of saying "I'm not sure that I want you to do a PhD in my lab."
 
 
* Sometimes academics use a concern about funding as a way of rejecting someone they feel would be a bad fit personality for their group. Because you can't argue with a lack of funding in the same way you could argue about "motivation" and "fit", and it avoids hurting the grad student. 

There are a lot of academics out there who don't have the best social skills. There are plenty professors who can diplomatically tell a prospective student that they don't have funding/space* and think you should join another research group. But to me this sounds like a professor who doesn't really want you to join their group but isn't managing to give you an outright rejection. He's stalling for time ("go away and think about this"), bringing up multiple concerns (funding, hobbies, do you know what you're getting in to). I mean, accepting someone into a research group isn't difficult ("You want to join our lab? Great! Let's meet next week to talk about projects."). 
It's like when someone is trying to dump you: "I don't know if I want a serious relationship," is a face-saving way of saying "I don't want a serious relationship with you." Except in this case "Are you sure you want to do a PhD in my lab?" could well be a way of saying "I'm not sure that I want you to do a PhD in my lab."
 
 
* Sometimes academics use a concern about funding as a way of rejecting someone they feel would be a bad fit personality for their group. Because you can't argue with a lack of funding in the same way you could argue about "motivation" and "fit", and it avoids hurting the grad student. 

There are a lot of academics out there who don't have the best social skills. There are plenty professors who can diplomatically tell a prospective student that they don't have funding/space* and think you should join another research group. But to me this sounds like a professor who doesn't really want you to join their group but isn't managing to give you an outright rejection. He's stalling for time ("go away and think about this"), bringing up multiple concerns (funding, hobbies, do you know what you're getting in to). I mean, accepting someone into a research group isn't difficult ("You want to join our lab? Great! Let's meet next week to talk about projects."). 
It's like when someone is trying to dump you: "I don't know if I want a serious relationship," is a face-saving way of saying "I don't want a serious relationship with you." Except in this case "Are you sure you want to do a PhD in my lab?" could well be a way of saying "I'm not sure that I want you to do a PhD in my lab."
 
 
* Sometimes academics use a concern about funding as a way of rejecting someone they feel would be a bad fit personality for their group. Because you can't argue with a lack of funding in the same way you could argue about "motivation" and "fit", and it avoids hurting the grad student. 

There are a lot of academics out there who don't have the best social skills. There are plenty professors who can diplomatically tell a prospective student that they don't have funding/space* and think you should join another research group. But to me this sounds like a professor who doesn't really want you to join their group but isn't managing to give you an outright rejection. He's stalling for time ("go away and think about this"), bringing up multiple concerns (funding, hobbies, do you know what you're getting in to). I mean, accepting someone into a research group isn't difficult ("You want to join our lab? Great! Let's meet next week to talk about projects."). 
It's like when someone is trying to dump you: "I don't know if I want a serious relationship," is a face-saving way of saying "I don't want a serious relationship with you." Except in this case "Are you sure you want to do a PhD in my lab?" could well be a way of saying "I'm not sure that I want you to do a PhD in my lab."
 
 
* Sometimes academics use a concern about funding as a way of rejecting someone they feel would be a bad fit personality for their group. Because you can't argue with a lack of funding in the same way you could argue about "motivation" and "fit", and it avoids hurting the grad student. 

I'm not sure that a Masters degree would add that much.  Especially if you have research experience already from your undergrad time. Personally, I'd always go where the money is.
It's perhaps a stupid question of me to ask - but are you sure about the MD route? Do you have medical experience and does it excite you as much as the chemistry research does? Something like a biomedical PhD might solve your issues of funding (because they would pay you), be less challenging that a combined MD-PhD course...but still allow you to make an impact in the world of medicine and do the research that you enjoy.

If your boss asks you to do something, you can't just not do it. You can try and negotiate ("I'm overloaded with course work this week, can I present my research idea at the next meeting instead?"), or ask for clarification ("What is involved in presenting a research idea in this group? Is there an approach you'd recommend for doing this?"). But if I was a professor who asked a student to come up with an idea, have the student either say "Yes" or not reply (which would imply consent to a lot of professors), but learn that the student hadn't done what I'd asked...I would be annoyed. If the student then argued with me instead of apologising, I think I would be even more annoyed.
In the OP's place, I would try and put more priority on my research, and focus on saving energy with the TA work (you don't need to be perfect as a TA, it might mean relaxing how strictly you grade the papers or how closely you look at the answers to cut down on the time spent with the assignments). After my first semester as a TA I did become a lot more efficient, simply through experience. As others have said, getting the perspectives of other PhD students is important, as is communicating with your advisor about expectations as soon as they ask you to do something. This doesn't strike me as an issue about suitability for grad school: rather, learning about how to balance all the competing demands within the PhD experience.

If your boss asks you to do something, you can't just not do it. You can try and negotiate ("I'm overloaded with course work this week, can I present my research idea at the next meeting instead?"), or ask for clarification ("What is involved in presenting a research idea in this group? Is there an approach you'd recommend for doing this?"). But if I was a professor who asked a student to come up with an idea, have the student either say "Yes" or not reply (which would imply consent to a lot of professors), but learn that the student hadn't done what I'd asked...I would be annoyed. If the student then argued with me instead of apologising, I think I would be even more annoyed.
In the OP's place, I would try and put more priority on my research, and focus on saving energy with the TA work (you don't need to be perfect as a TA, it might mean relaxing how strictly you grade the papers or how closely you look at the answers to cut down on the time spent with the assignments). After my first semester as a TA I did become a lot more efficient, simply through experience. As others have said, getting the perspectives of other PhD students is important, as is communicating with your advisor about expectations as soon as they ask you to do something. This doesn't strike me as an issue about suitability for grad school: rather, learning about how to balance all the competing demands within the PhD experience.

Yes, I get it. It happens a fair amount when I TA: my students are often applying to med school (and care about their GPA) or this is the first course where they are being challenged and getting lower grades than they are used to ("I'm an A student. Why aren't I getting an A in this class?"). 
Some of my strategies:
Name-dropping the professor. "Oh, Prof X specifically told us that if the student didn't show __ to only give them a B+" "Prof X grades several of the essays with the TAs every week." That's a great way of shutting down students who are threatening to escalate.  Telling the student to go and discuss it with the professor if they're still arguing in circles with you. "Look, I've explained this several times. If aren't happy with my explanation then I suggest you take it up with Prof X." If you're the one who brings in the idea of escalation, the students know it isn't something you feel threatened by. Stopping the argument if it goes in circles too many times. Just tell them that the discussion is closed. Don't indulge an argument for longer than useful. Thinking when I grade. Does this fit the rubric? If a student came back and argued about my grading, how would I justify myself? It makes me more confident in my decisions and ensures I've preformed my arguments before the student has seen their paper. From my experience, students only argue with me about grades once. When they see that I'm not the kind of person who budges they tend to knock it off, or at least refrain from arguing so doggedly next time. If students are repeatedly coming back at you to argue about every single assignment, then there may be an issue with how you're presenting yourself to them. Or they're just obnoxious sexist jerks. Those exist.
 

Maybe you could ask about scheduling a Skype session to talk through the paper, his feedback, and the revisions you should/will undertake?

Hey all, it seems that it would be a good idea to compile a list of of good questions to ask profs/grad students on visit weekends. If anyone has any insightful questions, I invite you to share in this thread! I will edit this post sporadically to include your suggested questions. I've started by including the questions I've thought up after working as an undergrad researcher in a competitive, sometimes brutal R1 lab, and I know there are a lot more things to ask--so help us all out by sharing your own questions!
To ask profs:
About lab life/students:
-What does an average day in the life of your grad students look like?
-How do projects get initiated?
-How many hours a week do your students tend to work? Who sets the expectations for work hours?
-Do your students hang out outside of lab?
-How many days do your grad students tend to take off from work on an annual basis?
 
About the prof:
-How do you correct your students when they make mistakes?
-How do you encourage your students when their chemistry is going poorly? How do you keep your students motivated?
-What motivates you about the chemistry of your lab?
 
About the training/chemistry:
-How do research projects get initiated?
-How long does it take for the average student to get their PhD? What generally is required for a PhD from a research standpoint?
-What kinds of problems do you think the lab will be working on in five years?
-How does your lab prepare students for successful careers in industry or academia?
-Does the lab have established collaborations with any groups?
 
To ask grad students:
To get the hindsight opinion on joining the school/lab:
-What do you like most about your PI? Least?
-What do you like most about your school? Least?
-If you could make the choice again, would you attend the same uni/join the same lab?
 
To get a sense for lab environment:
-Do you feel like you're friends with the other graduate students in the program and/or lab?
-Do you and the other grad students hang out outside of lab?
-Do you feel like your lab members rely on you and vice versa?
-What do you and the other grad students do for fun?
 

There are plenty of hands-on advisors that love to have weekly meetings with their students, who will expect weekly updates and are happy to talk to their students whenever they happen to knock on the door.
Sadly, it sounds like your advisor isn't one of them. In answer to the question in the title: I don't think you have a bad advisor, just a hands-off one. It is unfortunate that your advisor wasn't comfortable communicating their dissatisfaction with your meetings/drafts, but I'm afraid that happens a lot with academics. Advisors aren't obliged to help their grad students with things like SOPs, work-in-progress paper drafts or to drop other commitments to talk to their students (there are plenty of administrative or research issues that will be higher on a PI's priority list than an update meeting with an MA student).
My advice would be to avoid bringing this up with the DGS, since I don't think there is much they can do. As I said, they can't force a PI to do all the things you seek, and it will probably annoy your boss that you are escalating something that you should be able to deal with one-on-one. Go the office hours - I'd suggest monthly - and only submit "polished" drafts when you are close to the final product. Maybe a more senior grad student can look over your drafts and give some feedback?
 

For Montreal, I agree with fuzzy and also second the thought that most grad students live off campus, and rent in Montreal is very affordable for a big city!
However, if you are moving from a faraway country, I think it makes sense to start living on-campus at first so that's less things you have to worry about when you get settled in. If you are able to end your on-campus lease early, then that might be worth doing once you find a good place off-campus. I know that in Quebec, the typical notice to vacate is 3 months (unless it has changed since I was last there). So, in addition to July 1 being the most common lease end date, you would usually start looking for places to live 3 months before you want to move.

That's an over-generalisation. From what I've seen, there is a decent mix of lab sizes in the Top 10 Chemistry departments: from 10-40 people is the range. As others have said, you get a mix of very competitive lab environments, as well as ones that maybe work long hours but the people aren't as cut-throat. From what I've seen a single lab can also change its personality over the years: if there were grad students who didn't get along then it turned the whole lab toxic...but once they left everybody chilled out a bit. Or the PI was going crazy trying to get tenure...but ever since they were promoted they calmed down. 
I'll also just say it: it's OK to decline an offer from a Top 10 school in favour of a lower-ranked place (that fits you better). I know of folk who felt strongly conflicted, like they must join the best lab at the best university they were admitted to, even when they could see it was a bad match. There's no point being miserable in a lab, you can't do good science that way.

There are plenty of hands-on advisors that love to have weekly meetings with their students, who will expect weekly updates and are happy to talk to their students whenever they happen to knock on the door.
Sadly, it sounds like your advisor isn't one of them. In answer to the question in the title: I don't think you have a bad advisor, just a hands-off one. It is unfortunate that your advisor wasn't comfortable communicating their dissatisfaction with your meetings/drafts, but I'm afraid that happens a lot with academics. Advisors aren't obliged to help their grad students with things like SOPs, work-in-progress paper drafts or to drop other commitments to talk to their students (there are plenty of administrative or research issues that will be higher on a PI's priority list than an update meeting with an MA student).
My advice would be to avoid bringing this up with the DGS, since I don't think there is much they can do. As I said, they can't force a PI to do all the things you seek, and it will probably annoy your boss that you are escalating something that you should be able to deal with one-on-one. Go the office hours - I'd suggest monthly - and only submit "polished" drafts when you are close to the final product. Maybe a more senior grad student can look over your drafts and give some feedback?
 

I'd deal with the placement issue on a lab-by-lab, rather than a school-by-school basis. It's hard to tell from broad statistics whether (I) there are some labs that are better at placing their graduates than others (ii) if the people who wanted to get a tenure-track academic job (for instance) were able to do so. Some PIs have good connections with industry or seen as good breeding/training grounds for future faculty. 
You can look on group websites or LinkedIn to try and find out if people found good jobs quickly. And try to ask grad students at the recruitment weekend (they're more likely to be honest and actually know about placements than the admin or PIs). 

Don't be afraid of being a little bit jerk-ish! Or to simply read off a list of bullet points on a piece of paper when you're meeting with your PI. It could be that in your attempts to be polite you're in fact being so indirect that your PI isn't picking up on what you actually want, or thinks you are satisfied with responses they are giving. This is at heart a professional, business relationship - you don't need to apply small talk rules if that isn't helping. 
I'd try and figure out - either through former students or older grads/researchers in your Dept just what the deal with your PI is.* A low number of former graduate students could be down to several things: a lack of funding, students just not interested in that subfield of interest...or that the PI is difficult to work for. If there are a lot of students that started with your PI but dropped out then that would be a big problem. If most of their students graduated (under a reasonable timeframe/ended up with good jobs/etc) then it might be not as a big a problem. But you need to find out this information. 
* There's always someone in the Dept who knows all the juice and will be delighted to share it. Corner them in private and simply ask "Hey, it seems that Prof X has only graduated 5 students in the last 20 years, do you know why that is?"

I would suggest another tactic.  Instead of making a plea for these group conversations to be in English because I don't think that is going to get you what you want, I would instead try to invite a couple of your cohort mates for 1-on-1 outings to get to know them better.  It could simply be coffee, drinks, lunch, attending a school event together, some hobby you know he/she likes, etc.  Basically, if you can have a couple of these "dates" with at least 2-3 cohort mates, you'll get to know them better and might help ease the awkwardness in group situations.  The key point though is they need to be 1-on-1 so you'll mutually get to know each other better.
Another suggestion is that you can try to start another conversation with some of your cohort mates that don't seem to be participating much in the group conversation that you can't understand. Usually when a group becomes a certain size, it's difficult for everyone to be equally engaged so find the people that don't look like they are actively participating and try to engage them in a conversation. This is much easier if you have already had 1-on-1 time with them and you know something about them. One huge caveat is sometimes this works and sometimes this is a huge bust.  If I was going to try this, I would probably say something like "Hey X - did you read that y article?  Wasn't it [insert some adjective]?  Did you get the part about [insert something here]? What did you think about the Z part?" Target the least participatory person in the group conversation and go from there.  If s/he answers back - awesome.  If s/he doesn't engage - I might drop it and try another person on another day.
Good luck!

From my experience in chemistry...this happens, sometimes a lot. I can think of a few reasons why this might have happened.
Your PI wants to concentrate their research into something else. Even though what you proposed is a hot topic, there might be other things at stake. Maybe finishing up some established projects that can get turned in to publications before grant-writing season. Or even though it seems on paper to fit with what the group does, maybe in fact it is a little too different and would involve going into a research area that the PI doesn't want to go in to. Or else the hot topic field is too saturated and the PI doesn't think they can compete. The use of the word "complication" suggests that there is something else going on that you might not be aware of. Maybe the postdoc's initial experiment design was flawed, or the results didn't seem as conclusive to the PI as they did to others. Or maybe the experiments you proposed wouldn't go far enough to properly answer the research question. Some PIs are more hands-on with the direction of research. There are PIs in the sciences who encourage you to pursue your own research plan (with their approval, of course), and there are others who will ask you to try experiment X, or see if reaction Y works. It can vary from PI to PI. Some PIs only like to hear about research ideas that come out of their own mouth. There are different expectations about what a new grad student should be doing. A postdoc might have free reign to design their own experiments, since it doesn't really matter from the PI's perspective if the postdoc generates publications or even if the interesting ideas even work. However, a grad student in the sciences needs positive data to get their PhD. A PI might therefore want to closely control the student's research in the beginning - putting them on a proven, half-finished project to get good data quickly, or start a new project that the PI thinks will give a definitive does/doesn't work result without wasting too much time. If you obtain good data from the "safe" projects, the PI might then decide to give you more risky projects to try. Personally, I'd go ahead and do what the PI tells you without arguing. If you finish the allocated tasks to their satisfaction, work hard and earn their trust then there is a greater likelihood that they'll let you pursue your own ideas. Or maybe the PI will come back to the unanswered question later once they've thought about it some more. Or just do the experiments you want without telling your PI (if they really won't detract from the other stuff you're doing).* 
You can try to ask the PI about the "complication" from the perspective of trying to understand the science/field better, rather than arguing to get what you want. It will depend on the PI's temperament whether you get a detailed answer, though.
 
*I've done that. Turned out to be the best way of figuring out that my PI was right in the first place...

From my experience in chemistry...this happens, sometimes a lot. I can think of a few reasons why this might have happened.
Your PI wants to concentrate their research into something else. Even though what you proposed is a hot topic, there might be other things at stake. Maybe finishing up some established projects that can get turned in to publications before grant-writing season. Or even though it seems on paper to fit with what the group does, maybe in fact it is a little too different and would involve going into a research area that the PI doesn't want to go in to. Or else the hot topic field is too saturated and the PI doesn't think they can compete. The use of the word "complication" suggests that there is something else going on that you might not be aware of. Maybe the postdoc's initial experiment design was flawed, or the results didn't seem as conclusive to the PI as they did to others. Or maybe the experiments you proposed wouldn't go far enough to properly answer the research question. Some PIs are more hands-on with the direction of research. There are PIs in the sciences who encourage you to pursue your own research plan (with their approval, of course), and there are others who will ask you to try experiment X, or see if reaction Y works. It can vary from PI to PI. Some PIs only like to hear about research ideas that come out of their own mouth. There are different expectations about what a new grad student should be doing. A postdoc might have free reign to design their own experiments, since it doesn't really matter from the PI's perspective if the postdoc generates publications or even if the interesting ideas even work. However, a grad student in the sciences needs positive data to get their PhD. A PI might therefore want to closely control the student's research in the beginning - putting them on a proven, half-finished project to get good data quickly, or start a new project that the PI thinks will give a definitive does/doesn't work result without wasting too much time. If you obtain good data from the "safe" projects, the PI might then decide to give you more risky projects to try. Personally, I'd go ahead and do what the PI tells you without arguing. If you finish the allocated tasks to their satisfaction, work hard and earn their trust then there is a greater likelihood that they'll let you pursue your own ideas. Or maybe the PI will come back to the unanswered question later once they've thought about it some more. Or just do the experiments you want without telling your PI (if they really won't detract from the other stuff you're doing).* 
You can try to ask the PI about the "complication" from the perspective of trying to understand the science/field better, rather than arguing to get what you want. It will depend on the PI's temperament whether you get a detailed answer, though.
 
*I've done that. Turned out to be the best way of figuring out that my PI was right in the first place...

Here's some v. anecdotal, small sample-size observations of mine, based upon the difference between an Ivy League/Top 10 (IL) and a Top 50 (T50) school.
IL has a better class of invited speakers. More likely to invite for seminars top-ranking American & international professors from similar top-tier schools. As a result, the grad students & postdocs are exposed to more cutting-edge research, big names and the kind of presentations that reel in awards, prestige, etc. Grad students who then meet with or go out to lunch with the invited speakers learn how to act like a big name, make great connections, etc. IL research groups have more group meetings. Not just research updates but they seem more likely to give literature presentations or thematic subject intros (a lot of them are posted online) or "synthesis challenges" if you're in the synthetic chemistry subfield. Thus as an IL grad student you may get training in a more diverse set of skills and have more opportunities to strengthen/develop your scientific knowledge. There exists "department wide job-seeking intelligence". The students in one IL department have a well-publicised strategy for submitting postdoc applications to maximise the chance that the target PI will read their materials. It was pretty clever and widely adopted. I've not heard about this sort of thing where I study.  Good universities are often located near (i) other good unis (ii) companies. Think Boston or the Bay Area. Which means that it's easier for recruiters to come to the big name universities or for you to gain exposure to invited talks at nearby universities too, etc.   
That said...
Not all IL labs are "success factories".  If you work for a well-respected PI at a T50 school and work hard, you can graduate with a CV that's just as good (if not better) than if you went to an IL.