I guess you got the interview invite as I rejected my admit on 17th April. Hahahaha, but I can be wrong. Anyways I would love to help you out.
Research about ur interviewer (pssst LinkedIn) also about the school.... questions will be normal, but you must hit the ball out of park with ur knowledge about the school, If u are able to make them feel that you know as much as they do, then you are in....(sites: Bloomberg MBA ranking, FT 2014'15 MBA ranking, QS MBA ranking... Wiki). Base your questions on the interviewer and how the school will help you achieve your goals... don't ask them things that you can easily find on their website.
Last but not the least... Project confidence and smile a lot... they are wonderful ppl.