I had a different experience from the poster above me. My interviewer was 10 min late, and then the interview itself was an hour instead of the allotted 30 minutes. By the time I was done I couldn't find any of the other interviewees because they had already left to wander around the school. The ethics essay was very easy, so don't stress about that.
For me, the interview was very stressful. They asked me a lot of hypothetical answers, and questioned me about healthcare problems. They asked me about all of the problems the physicians I shadowed had, and then asked how they fixed them. I guess it just depends who the interviewer you get is. Hopefully yours is on time! Good luck!