Hey Miss B,
Congrats on your interview! You've come a long way. You will get three interviews, one with the director of admissions, one with a med student, and another one with the faculty.
The style of interview really varies depending on your interviewer. The one with the director of admissions is adminstrative. He just wants to know if there has been any changes to your application since submission. From my own experience, everyone there was very helpful and welling to offer their insight to the school.
My advice to you is to get a good night sleep the day before, because it will probably take the whole day. Best of luck to you!