The interview is pretty conversational! They do see some of your application - they asked me questions about some of my experiences. You typically have two faculty members and one 4th year student as your interviewers, so your experience will depend on them. I had a wonderful time, one of my interviewers was the professor who turned out to be my favorite this semester, so that was awesome. Some faculty can be intimidating of course, especially since you don't know them. It really is a be yourself kind of interview though. They want to know about you and how you would fit into the class.
Business attire is typical, nothing specific I don't think. I wore black pants, a dark green blouse, and a gray blazer. Most of the ladies seem to wear heels but I walked to the school from my hotel and wanted to be comfortable on the tour so I wore flats.