Congrats on the Interview!
I was accepted EA to CMU (start in May)! We had an EA reception a couple weeks ago and it was pretty relaxed and informal even though we dressed up. During the reception we took tours of all the PT areas, met with current students and asked questions, we then met with faculty who answered any questions. It seemed that even though we had accepted a spot in the class inmost cases the faculty was trying to sell us on the program. The facilities for the program are spectacular and the technology is endless. I had been sold prior to attending the reception, but even more so now. I know this doesn't help with the interview, but I would guess the format would be similar. However tailored to asking you questions and getting to know you beyond your numbers. If you have anything specific about the program feel free to ask. You can PM me as well if you'd like.