hey,
congratulations on recieving an interview at drew!
as far as the interview goes, it is pretty laid back. when you arrive you will sign up on a sheet and they interview via first-come, first-served. most of the time one gets interviewed by one faculty member, sometimes a student does the interviewing as well. they have several questions that they ask everyone, from what kind of household did you grow up in, to what your commitment has been to the underserved, or stuff similar to that. my interviewer was really nice and it wasn't too intense. i wasn't thrown any ethical questions, or stuff that was off the wall, it was more of your typical, "why do you want to be a doctor?", type stuff.
before the interview there are a couple videos that they show that talk about the school and specifically about dr. drew, he was quite an amazing man. a tour is also given of king/drew hospital and of the drew campus. i highly recommend setting up an appointment to see the ucla campus as well, if you haven't already. they are both quite nice.
as i am sure you know, they are looking for people dedicated to serving the underserved, more so, the underserved of the inner-cities.
i hope that this helps, and if you have any more questions, just post them. i like this school quite a bit and i am very much hoping to attend. it is a wonderful program and only selects a few.
best of luck.