magnanimous

I wouldn't take the risk, especially if funding isn't guaranteed. Try to boost your credentials you can get into the PhD programs you really want to.

Hi @marmend! I tried searching around and couldn't find a dedicated off-campus housing map, but here is a list of all of the off-campus neighborhoods, and if you combine that with the interactive campus map, you might be able to go from there! Also, I don't think there are landlords dedicated to any specific area. . . They tend to be focused right on central campus in a variety of places (probably so they can reach as many students as possible).http://housingannarbor.com/ and http://www.johnwcooper.com/annarbor/offcampushousing-universityofmichigan.htm might be helpful for a starting point since they're collections of many of the housing companies and landlords in Ann Arbor, and you could probably compare the addresses of any houses or apartments you're looking into to the neighborhoods and points on the map just to get an idea of distance. Those neighborhoods are also searchable on the off-campus housing website, but the selections there are a bit more limited.
Hopefully this helps a bit, and feel free to PM or let me know if you have any other questions!

Another wait list success story here!!
I was actually pretty pleased with being wait listed by my top program after a less-than-impressive application cycle and hearing that the program had only offered three acceptances this year. I emailed after being wait listed just to say that it was still my top choice and I wouldn't make a decision until hearing from them. My POI contacted me to schedule a call about a week later, and offered me a spot while we were on the phone. I got an amazing fellowship offer a few days later.
Like I said, I didn't feel so great about my chances this year, and was beginning to consider back up plans before getting off this wait list (my only other acceptance provided a generous first year fellowship, but it wouldn't have covered the full cost of living, and funding for subsequent years wasn't guaranteed). This totally feels like a one in a million chance that is the result of finding a really close research match and someone else happening to decline. PhD apps are SUCH a crapshoot!

I don't think it's necessarily a huge problem that you don't have undergrad experience in Education, as long as you can discuss in your SOP why you want to pursue the degree, what about the field you have particular interests in, and how you think the coursework that you've had already has led to that. I would suggest getting a letter from either 1, 2, or 4.
In the case of professors 1 and 2, did you have extensive contact with the TAs? I've heard of professors and TAs writing joint letters and both signing (because oftentimes students get to know the TA of a large class way better than they get to know the professor, and vice versa), or the professor having the TA write the letter since they know you and your work better and then just signing off on it.
For professor 4, I feel like they might be able to write you the best letter because, as you mentioned, they know you best, and you wouldn't have to go through TAs like I suggested in the other two options. Since it's been a few years since you asked for the last LOR from them, I don't see why they would be annoyed by you asking for another one, but then again you never know. If you feel like they would be able to speak positively about your work ethic and academic strengths regarding the program, then I would definitely ask this professor.

I can't believe I get to say this.....
BUT I GOT IN TO MY TOP CHOICE*!!!!! 
*one of two top choices
Wow. Unreal. 
The stars really aligned for me as I hadn't had any offers before getting this great news. 

I chanced upon this while I was searching for some information. Not too sure if anyone knows about this? http://www.phdstipends.com/results

It really depends on the school. My PhD program didn't pay travel costs for admitted students but did welcome them to visit.

I've been doing a bunch of googling and looking through threads on here, and this is the categorized list I've come up with that I plan to draw my questions from. (I might be over-thinking/over-preparing.)
 
Graduate Students
Research
What research are you working on? How quickly were you able to start your research?
Life/social
How much of a student community/social life is there (including within cohort)?
Is it an inclusive environment? Have there ever been problems with harassment?
Where do you (and students in general) live? How is living here?
What is the area around campus like? How are the housing options?
Is the university helpful with finding housing?
Is the stipend enough to live on?
Advisors
How is working with your advisor? (intentionally open-ended)
How would you describe your PI's advising style? (hands on/closely supervised or hands off/independent)
What strategies have worked well to maintain a successful relationship with your advisor?
How available is your supervisor? How frequently do you meet with your advisor?
Does your supervisor support support interest in a career outside academia?
How regularly/quickly does your advisor publish?
Would you choose this advisor if you were doing it over?
Program/University
What do you think of the program? Biggest pros and cons?
How easy/hard is it to customize the program? (i.e., taking different courses)
What do you think of the courses? Useful content, well taught, relevant to your research/goals?
How big is the program?
What would you change about the program?
Does the environment feel more collaborative or competitive? Are students generally collaborative or competitive?
How easy/difficult was the process of joining a lab?
What are responsibilities of TAs like? What is the workload/time commitment? How many terms do you TA?
Group/lab
How would you describe the lab group? (Intentionally open-ended)
What is the culture in the lab? How much time are you expected to spend in the lab?
What kind of schedule do you work?
How much collaboration is there within the lab?
Other
Are you happy here?
What do you wish you had taken into consideration when making your decision about where to attend?
Who is on your committee and why?
Do you get to attend conferences?
How is it being a female in this generally male-dominated department/university/field?
Professors & Potential Advisors
Students
Do students create their own projects or work on something already developed/in progress?
What are the expectations for a graduate student in your lab? (i.e., working from home, fixed hours)
What advice would you give to a student who wants to be successful in your program? Are there any specific pitfalls to be avoided?
How much do students RA vs TA? What is the funding structure/guarantee for students?
How often do you sent students to conferences?
How long do students in your lab take to complete?
What do students from your lab typically do after graduation?
Research
I hear you study X. I've only studied a little bit of that so far, but I remember learning about Y. Can you tell me a little bit about your work?
What are your current projects?
What research projects do you have that would be looking for graduate students?
What directions or projects are you thinking about for the future?
University
What is the big picture/goal/focus/priority of the department?
What's the biggest strength of the program?
What professional development services are available?
How/when are students paired with advisors?
What percentage of students complete the PhD? Pass quals?
What are responsibilities of TAs like?
Would any of my master's coursework transfer?
Other
How is your lab organized?
What collaboration goes on? Within/between labs, departments, other schools?
How would you compare this program to X and Y?
Is there funding available for attending things like conferences or summer schools?
Do you have lab/group meetings? What do you discuss? (papers, research in progress)

We recently had interview day at my program. After the day ended, we met with all the faculty members and were asked to briefly provide our thoughts and any potential red flags we noticed about applicants. Feedback included social awkwardness, being under dressed, saying judgmental things, asking great questions, being personable, having admitted to not being interested in research, being (un)able to coherently discuss their research interests, (not) being a good fit, etc.
No matter how casual your interactions with current graduate students may seem, remain professional; the faculty will likely ask for their input on you. The moment you step on campus, act as though you are being interviewed the entire time. If you are staying with a current grad student, the same advice follows. Don't say anything to anyone that you wouldn't say to a faculty member. I know of several instances where students or staff affiliated with a program told faculty about unfavorable things applicants said/did, which resulted in rejections (admitting to not liking research, fighting over where to sleep at a grad student's apartment, being mean to a secretary, etc).

OP-also a young current senior undergrad in the middle of applying to PhD programs. So far I've gotten 5 interviews out of 7 applications. Haven't heard back about acceptances/rejections yet as I'm still interviewing. 
Some people have recommended time off to me when I told them my plans, but they also had different life trajectories than me. Not saying that someone with my background wouldn't benefit from time off, but when your parents are well-off and have MDs/PhDs/JDs then you can afford for them to support you while you ~discover yourself~. All the reasons people told me they benefitted from time off (self-discovery, getting a job because they never worked a day in their life, being independent, etc) are all things I don't need time off for because I've already experienced it. Life comes at many people fast, and by the time they're 20/21 they have more maturity and have had more life experience than people twice their age even. Age does tend to correlate with maturity and experience, but it's not 1:1. 
The only reason I'm worried about being young and in graduate school is with regard to colleagues in my program/cohort. Now that I'm 21 I don't have to turn down outings at bars because I'm finally old enough to even walk in the establishment, even though I don't drink. Being young, specifically under 21 put a damper on my relationships with coworkers (early-mid 20-somethings). I'm worried that they'll see me as too young to hang out with or form relationships with, even though many students early in their PhD are only 2-3 years older than me. But that's a (I would say frivolous) personal insecurity, not something that reflects my actual maturity or capabilities. 
 
tl;dr Listen to yourself and do what's best for you. Just make sure that the voices you're listening to are actually yours and are true/accurate. Good luck!