peachypie

Describe your research, what are you hoping to do with a PhD, why a PhD, why this program.  Those are the big ones.  Also I found that the more confident you are and the more you can handle those big questions the more they lay off of you.  I didn't have any scary interviews even though I was warned so and so would be tough and kind of intimidating.  If you go in and they know you know your stuff they back off and just love to chat with you.  Be pleasant and honest.  I always answered where else I had interviewed and which other places I would be yet.  I did not give any indication of what my top choices were but always explained what about their program makes me interested in them.  So tell them the list and say, some of the things I am looking for are x,y, and z which is why your program is of interest to me.  Remind them, you are interested in them too!
Other than that just go with the flow.  If you have any weak points be prepared to answer them and give an explanation for them.  Once you go through the first one and get the jitters out you'll realize how fun it can be.  Remember that they already like you or they wouldn't bring you out to see them.  Now you just have to show them that you are what you say you are, and that you can do it.  That is really what they are looking for.
Best of luck!

I'm going to chime in only since I have a friend that gave me some advice when she applied.  (she is now a postdoc).  She got an interview to a top 20 school and she had a friend affiliated with the program.  She found out later she BARELY got an interview, but apparently knocked their socks off in the interview and was one of their top candidates.  I will say that there are already the rankings or the people they want right off the bat, but once you are in an interview you can either make or break your case.  the interview is about seeing if what you are on paper is what you are in person.  Then additionally if you are really awkward, inappropriate, or a bit off hinged.  If you have a bad personality no matter your stats you'll be out.  So yes most people go to the interview and stay where they are, but I bet maybe 25-30% could easily move.  Schools will have their favorites coming in but that doesn't mean you are sentenced to last if that is where you started.  everyone goes back to equal playing field once you get to the interview.  

I'm not going to contribute anything that hasn't been already said but in all honesty I am wondering if you actually want to interview at this program or not.  To me everything you've communicated is that something else is more important.  There is no way that a new part time research job should rank higher than a PhD interview with a professor offering you multiple interview dates.  Don't take this the wrong way but you have your priorities really messed up.  I take it you want to get into the other department of the same school of the part time lab that you are hoping to do your PhD in.  I hope you realize two things: 1.  people in the same school talk so hopefully this doesn't mess you up when it comes to admission to that department and 2. I believe this interview is just a back up to your other more interested PhD placement.  I'd be surprised if you were offered admission to this program at this point.

Describe your research, what are you hoping to do with a PhD, why a PhD, why this program.  Those are the big ones.  Also I found that the more confident you are and the more you can handle those big questions the more they lay off of you.  I didn't have any scary interviews even though I was warned so and so would be tough and kind of intimidating.  If you go in and they know you know your stuff they back off and just love to chat with you.  Be pleasant and honest.  I always answered where else I had interviewed and which other places I would be yet.  I did not give any indication of what my top choices were but always explained what about their program makes me interested in them.  So tell them the list and say, some of the things I am looking for are x,y, and z which is why your program is of interest to me.  Remind them, you are interested in them too!
Other than that just go with the flow.  If you have any weak points be prepared to answer them and give an explanation for them.  Once you go through the first one and get the jitters out you'll realize how fun it can be.  Remember that they already like you or they wouldn't bring you out to see them.  Now you just have to show them that you are what you say you are, and that you can do it.  That is really what they are looking for.
Best of luck!

Pretty bad form to cancel an interview especially the way you played it out.  An alternate weekend for a school is going to very likely the same "feel" as the first weekend interview; especially since there are usually more than one applicant there. 
Stick to what you promised to school A (think how awful you'd feel and respond if school A decided to cancel you for another applicant they thought they liked better after they told you to come!).
Inquire about an alternate weekend for school B. 

Honestly, it's a crappy thing to do to School A. Try to find another time to visit School B.

I agree with @peachypie... you aren't choosing potential PIs at all, even at small programs.  That's what rotations are for because you have to mesh well on a personality level.  If that's what you're looking for, you might be a tad disappointed when you get to grad school.  Obviously you should have people you're interested in and may have met them in passing at a dinner or something.  But to expect to have interviewed with them?  It's a teensy bit closed minded to think that this is the way you choose grad school.  What if they don't have funding next year or decide to teach more or go on sabbatical or are an awful mentor or decide to take their research in a direction you don't want to go in?  My interviews include ~50% people I expressed interest in and others that are on the admin committee or are available or some other criteria.

You would never be able to determine the fit of a lab from a 30-45 minute interview.  PIs and labs are much more complex than that.  That is your naivete showing.
I'm not being antagonistic but this same exact question has come up a multitude of times in this thread alone.  I'm surprised we are still getting posts about it, just kind of like the clothes stuff.  All of that is just evidence that people are focusing on the wrong things when going through this process.
You are a grown adult and you are about to be a graduate student.  You clearly are smart enough to figure out how to talk to your POIs, you actually had the answer all along by saying...meeting/talking with profs during your visit.  Maybe during a social or poster session, lunches and dinners or happy hours is your time to go and introduce yourself.  Instead you said that this scheduling was possibly due to "getting the leftovers".  You had a negative approach about it, regardless of what you say now.  
Again, I will emphasize....interviews should be about what school/program is best for you.  Not individual PIs.  Do not fall into the *very frequent* trap that you go to a school to work with someone you have in mind.  It VERY frequently doesn't work out the way you anticipate.  When or IF that were to happen you will have wanted to pick a program that even if a PI or lab does not work out will still give you very good training and is a school and program you feel supports you and fits your lifestyle as well as your academic approach.  Again and again and again....do not pick a school based on a lab.  That is putting the cart before the horse.

You would never be able to determine the fit of a lab from a 30-45 minute interview.  PIs and labs are much more complex than that.  That is your naivete showing.
I'm not being antagonistic but this same exact question has come up a multitude of times in this thread alone.  I'm surprised we are still getting posts about it, just kind of like the clothes stuff.  All of that is just evidence that people are focusing on the wrong things when going through this process.
You are a grown adult and you are about to be a graduate student.  You clearly are smart enough to figure out how to talk to your POIs, you actually had the answer all along by saying...meeting/talking with profs during your visit.  Maybe during a social or poster session, lunches and dinners or happy hours is your time to go and introduce yourself.  Instead you said that this scheduling was possibly due to "getting the leftovers".  You had a negative approach about it, regardless of what you say now.  
Again, I will emphasize....interviews should be about what school/program is best for you.  Not individual PIs.  Do not fall into the *very frequent* trap that you go to a school to work with someone you have in mind.  It VERY frequently doesn't work out the way you anticipate.  When or IF that were to happen you will have wanted to pick a program that even if a PI or lab does not work out will still give you very good training and is a school and program you feel supports you and fits your lifestyle as well as your academic approach.  Again and again and again....do not pick a school based on a lab.  That is putting the cart before the horse.

So all of your other interviews have 100% of your interviews with potential POIs? is that what I'm hearing.  so like you have 4-8 POIs at each university and you've managed to get scheduled with all of them? 
They do their absolute best but things come up.  Umbrella programs most certainly may operate differently than smaller,individual program interviews.  If this is throwing you off of BU then I'd suggest you don't interview with them.  I have said it before, and will now say it again.  Do not go to a school with the intent on working with one specific person.  This often doesn't work out.  Things happen: faculty move, faculty lose funding, faculty take 2 students the year  before you instead of one.  It sets you up for failure.  What you should do at an interview is look at the personality of the students and faculty and general feel to make sure its a good fit for you as a person.  Are you a type A person but everyone around is you super passive?  Probably not going to be a good fit.  Also people rotate through their previous POI and realize they would hate working for them.  Finding a good fit in a lab to be successful is way more about the relationship and personality of your lab and you and a lot less about the research being "interesting" or "your favorite".  We say this every year to grad students and they come in thinking that its all about the research.  Well its not.  So you never know what your potential profs will be like once you work with them.
Try to be a bit more open-minded and see the bigger picture here.  If you feel that BU has screwed up in this regard: cancel it and move on.

So all of your other interviews have 100% of your interviews with potential POIs? is that what I'm hearing.  so like you have 4-8 POIs at each university and you've managed to get scheduled with all of them? 
They do their absolute best but things come up.  Umbrella programs most certainly may operate differently than smaller,individual program interviews.  If this is throwing you off of BU then I'd suggest you don't interview with them.  I have said it before, and will now say it again.  Do not go to a school with the intent on working with one specific person.  This often doesn't work out.  Things happen: faculty move, faculty lose funding, faculty take 2 students the year  before you instead of one.  It sets you up for failure.  What you should do at an interview is look at the personality of the students and faculty and general feel to make sure its a good fit for you as a person.  Are you a type A person but everyone around is you super passive?  Probably not going to be a good fit.  Also people rotate through their previous POI and realize they would hate working for them.  Finding a good fit in a lab to be successful is way more about the relationship and personality of your lab and you and a lot less about the research being "interesting" or "your favorite".  We say this every year to grad students and they come in thinking that its all about the research.  Well its not.  So you never know what your potential profs will be like once you work with them.
Try to be a bit more open-minded and see the bigger picture here.  If you feel that BU has screwed up in this regard: cancel it and move on.

Thursday night: casual (sweater/nice shirt and either khakis or like even nice jeans) 
interview day/any day you are meeting or around faculty: business casual.  NO JEANS.
Saturday/Sunday: any time with just grad students can be more comfortable and should reflect what you are doing?  Walking campus tour? Casual/comfortable, going out to bars or going to a sporting event/music can be casual.  Just be reasonable.

doesn't really work like that.  you aren't interviewing to work with specific people, you are interviewing to enter the graduate school.  Many people do not get all of their interviews with people in their field as often faculty on admissions committee need to interview students.  Also it is a matter of availability of faculty those days, not all faculty are around or free.  This has come up time and time again in this sub and people need to stop acting like an interview at a school is all about finding their next advisor, that is not the point of this.  Its great if you get to meet with someone you are interested in but by NO means should your interview schedule give you an idea of where you'll work or what dibs you or some other students got. 

doesn't really work like that.  you aren't interviewing to work with specific people, you are interviewing to enter the graduate school.  Many people do not get all of their interviews with people in their field as often faculty on admissions committee need to interview students.  Also it is a matter of availability of faculty those days, not all faculty are around or free.  This has come up time and time again in this sub and people need to stop acting like an interview at a school is all about finding their next advisor, that is not the point of this.  Its great if you get to meet with someone you are interested in but by NO means should your interview schedule give you an idea of where you'll work or what dibs you or some other students got. 

doesn't really work like that.  you aren't interviewing to work with specific people, you are interviewing to enter the graduate school.  Many people do not get all of their interviews with people in their field as often faculty on admissions committee need to interview students.  Also it is a matter of availability of faculty those days, not all faculty are around or free.  This has come up time and time again in this sub and people need to stop acting like an interview at a school is all about finding their next advisor, that is not the point of this.  Its great if you get to meet with someone you are interested in but by NO means should your interview schedule give you an idea of where you'll work or what dibs you or some other students got. 

I don't think vene ever said they went to an LA based school that is part of the CSU system. 

One masters applicant posting many times in the last few pages doesn't mean there are tons of masters students. 
I don't check results thread, unfunded phds in bio are rare in many of the top schools.  Top 30-50 would be all pretty much 100% funded.
Also your is possessive, "you're incorrect" is what you  meant to say.
I don't know your state school.
I never said I was from california.  I'm not an LA native, so I don't know why you are faulting me for that or how it factors into your argument.  There have been aarticles from UC system schools in bio that show they post about 10-15% international students, so I haven't found any at about 40% as you had mentioned.
You must be basing your whole understanding of graduate schools on UC system which isn't fair to assess all the programs in the country off of the public system in california which probably is working with a tighter budget for all of its schools in the system that are working at full capacity.  I'm not choosing to ignore reality, but I don't think that your initial comment that international applicants actually give school money is an approrpriate assessment for many PhD in biology graduate programs, at least at the more well-funded schools.

It should be fairly obvious then, based on your itinerary, that you will meet with faculty (anywhere from 5-8) throughout the course of the interview day.  They will be one on one interviews that last anywhere from 30-45 minutes.  Again all these details will be given in your itinerary.  Have you received them already? 
I typed up a whole paragraph of the things that faculty care about before I realized it is all questions you should be able to answer if you are prepared for graduate school anyway.  Me spoon feeding you the types of questions and what the expect of an applicant does not do any service to the school or you as an applicant.  I would be happy to answer specific questions but this isn't a final exam and I'm not giving out a study guide so people can "do their homework" to get into graduate school.  Prove to me you have thought about this and are coming with specific questions like you've taken time to understand the process and what you are embarking on.  then I'd be happy to guide you or talk about specifics.  Most graduate programs will be very similar in their approach so you don't need to ask a student from each school/program. 

You say the "bubble in which academics live", but I think this is a case of the opposite. 
Most people offering an interview for a job wouldn't put up with this much rescheduling, not when they have plenty of candidates who want the spot. 
Frequently job interviews, even on the other side of the country, expect you to be able to drop what you're doing and show up when they want you to. If you can't do that, chances are you won't get the job. I even know companies that assume that about half of the applicants invited for an interview won't show up, and use that as a way to weed out the serious candidates from the non-serious ones.
So rather than the professor being in an academic bubble, I'd argue that in this case the OP (and perhaps yourself) are expecting a job interview and offer in academia to be different than a job interview and offer in the rest of the world. 

I would argue it's seen as a measure of priorities. 

I understand you are from a different field so I'm guessing that is why there may be some differences.  In the biological sciences often acceptances are offered following an in person interview.  People who do not interview (at least that I know of and of course there can be rare exceptions) are not offered admissions.  Skype interviews are reserved to international applicants unable to attend interview weekend and extenuating circumstances (i.e. blizzards that shut down travel and cause an applicant to miss an official interview without any chance for rescheduling).  I was working a full time job when I interviewed and took time off, everyone at my job understood this was how it worked and although I missed work (often wed-friday) I often came in on Sunday if I got back by then to start work for the week so everything didn't end.  People also interview when they are still undergrads, missing class and having to make up exams or labs.  It is part of the field, for you to say we are all tone deaf in our response may be a reflection of the differences between a biomedical/biolgoical science graduate interview and a  classical archaeology graduate interview; to which I say I would expect more humility for a subject you have no experience in.

I'm not going to contribute anything that hasn't been already said but in all honesty I am wondering if you actually want to interview at this program or not.  To me everything you've communicated is that something else is more important.  There is no way that a new part time research job should rank higher than a PhD interview with a professor offering you multiple interview dates.  Don't take this the wrong way but you have your priorities really messed up.  I take it you want to get into the other department of the same school of the part time lab that you are hoping to do your PhD in.  I hope you realize two things: 1.  people in the same school talk so hopefully this doesn't mess you up when it comes to admission to that department and 2. I believe this interview is just a back up to your other more interested PhD placement.  I'd be surprised if you were offered admission to this program at this point.

And the understatement of the day award goes to you.  Wait until you realize how many people master out.

And the understatement of the day award goes to you.  Wait until you realize how many people master out.

Yeah this is definitely something that happens (faculty leaving).  Webpages can be wildly out of date, as I believe you are realizing right now.  Many times a professor moves and either the graduate school or their own personal webpages do not reflect their current appointment.  This can lag from weeks to months to almost a year easily.  This is another classic reason why you do not apply to a school to work with just one individual.  Not saying you did, but this is the perfect situation that arises that leads to an unhappy student.  I don't think you  need to contact the professor.  If he/she is no longer associated with Weill Cornell then it doesn't quite matter for your purposes in relation to your Weill Cornell interview.  That is also something that if you chose to go to that school you can investigate further; however, it appears from what you've noted that this professor is no longer associated with Weill Cornell.  I don't think professors think about potential graduate students they've never been in any communication with about regarding a transfer.  People take jobs or leave jobs for a lot of reasons and they do not need to, nor should they be, expected to do so on an arbitrary timeline for something like this.  They also for reasons of job security have no need to make this known to anyone that isn't on a need to know basis.  Maybe had you contacted him ahead of time, if he was this important, you would have known many months ago about this.  I would not ask the coordinator about for a few reasons.  One it shouldn't matter.  If you are interviewing there you should be interested in the school regardless of this one person being there or not.  Don't let them realize that you are only interested in working with him.  They may still interview you but they may not admit since they would guess you'd decline if the professor is not there.  Also its not important, it happens.  I had people in my SOP that were associated with the program when I applied that I later found out had left during those few months, it happens.  Be professional about this.  If you are not interested in this school because this one person isn't there maybe you should contact them and ask to withdraw your application and cancel your interview.  If you are still interested in the school even though this person is no longer associated with the program then go ahead on the interview and drop any follow up questions about this one person.