You're first question is kind of funny because while most of my interview questions were standard questions (why this program? what are your future goals? tell me about yourself? what is your experience in research?), one of my interviewers gave me two chemistry questions to solve.
It wasn't that hard to figure out the answers, but was pretty unexpected and slightly stressful. So, like all interviews in general, just be prepared for the standard questions, and realize that some interviewers like to throw you a curve ball, and try to deal with that the best way you can.
I did the biomedical research track, which I feel is the best track. Anatomy track students are fairly isolated, as there is only 1-2 of them a year. In contrast, there are around 10 biomedical track students each year who take the same classes together. If you don't mind being with yourself all the time, go for anatomy track. However, if you like to be part of a bigger group you should definitely go for the biomedical track.
You'll end up taking Biochemistry, as all students do, and from there you'll branch off into either Physiology I and II, or Biochem II and Microbiology/Immunology. Which courses you take depend largely on the department in which you complete your research.
You should also realize that while previous classes were able to transfer credits from M.S. program to the D.O. program, the curriculum is changing in 2012/2013. They are transitioning from a discipline-based approach (biochem, anatomy, physiology, pathology), to a presentation-based approach (sore throat, dizziness, nausea, chest pain) much like what is currently in place at ATSU-SOMA. Thus, if you decide to come here for medical school, your credits from the M.S. program would likely not transfer.
Whatever you do, don't be nervous. You sound like an ideal candidate. It seems like a long road ahead, but it will go by fast. Enjoy the ride.
If you have any other questions, just PM me.