Yeah, I finished last year. Words of wisdom...hmmm...
Okay, so as far as classes and professors, I had Tuts for physics and thought he was great. Lots of cute demonstrations--even one with a monkey. For G-Chem I had a guy named Morrow, who I don't think is there any more (if he is, avoid his class like the plague!). The other guy, I forget his name (Pine? Vine? Something like that...) I've heard not such great things about either. If there's another option, you might want to look into it. For Orgo I had Virginia Cornish, who was fine, not spectacular, but fine. And Colin Nuckolls for second semester, who I liked a lot, but he had mixed reviews among other students. For Bio, everybody takes Mowshowitz, who is the BOMB-diggity! For her class--in fact for every class--I HIGHLY recommend getting getting your hands on old exams for each of your professors so that you can get a feel for their style of testing before you actually start taking the real ones. For many of these classes there are only 2 or 3 tests thoughout the whole semester, so taking a hit on just one test because you weren't familiar with the kinds of questions they ask and the tricks they use (Mowshowitz uses lots of tricks), can end up hurting you pretty badly.
When I was there, the advising was not so strong. But they've apparently made some significant changes to the administrative staff and the advising structure. Either way, you should be proactive about getting feedback and counseling from the program leaders. Ultimately, one of the advisors will be writing your committee letter, which goes out to all the med schools you apply to, so you should establish a relationship with one of them fairly early on.
They will probably push you to get involved in clinical volunteer work and lab research pretty early on, and it's frankly a very good idea. Second year will be very busy, between Orgo, Bio, labs, preparing for the MCAT, and perhaps working through a first draft of your personal statement, so if you want to take some time off from volunteering/lab work, you'll want to get started with those pretty quickly in your first year so you have a good amount of exposure under your belt come application season. There are a number of different volunteer opportunities that will be pitched to you. St. Luke's is right near Columbia, so it may be convenient, however, I hear that it's a bit disorganized. St. Vincent's is a highly structured program that takes you through a series of rotations through many departments of the hospital. The down-side is that it's a two year commitment (I think, maybe it's a year-and-a-half) and is pretty inflexible about rescheduling. I chose to volunteer at Bellevue Hospital Center, because they have a very busy emergency room with the largest trauma slot in the northeast, the volunteer commitment is more malleable and only lasts 6 months (though you can stay longer if you like), and finally because Bellevue is an internationally recognized name. All the Admissions Committee members who read your AMCAS application will have heard of Bellevue, while that is not necessarily true of some of the other New York hospitals.
Finding a good bench science position is a little trickier. I did a lot of surfing on the net and picked out some PI's (principal investigators) that seemed to be doing interesting work. Also, on Cornell's site they often post pictures of their PI's, so I also chose people that looked nice (lab folk can be a little isolated--working mostly with mice and spores, and not so much with humans--and often develop interesting personalities). You're probably best off talking to other people in the program and recent grads, and asking about their experiences and maybe getting a referral to their old PIs. I could recommend mine, since she's super intelligent and will keep you very busy and learning a lot, but she can be a bit difficult to work with as well. She's very cool once you get to know her, but a bit of a dragon-lady.
Anyway, I hope some of this stuff helps. Best of luck to you, and let me know if there are any other questions you have.
Cheers,
Lefty
P.S. You should totally go away during the summer before Orgo/Bio. I spent several months in Ecuador learning medical spanish and volunteering in a public hospital there. Aside from being an incredibly fun time, full of adventure, it was great exposure to a very different health care system and medical culture. If you're interested in that kind of a program, I can put you in touch with some people and recommend a great host family.