In for round 2. Good luck everyone!
I had my interview yesterday (out of town, off-campus). The interviewer was very relaxed, friendly, and engaging. It was much more conversational than I had expected, with less clear-cut question and answer, and more a free-flowing conversation. We spent a good 30 minutes discussing the school, his experiences there, etc.
I wore business casual, but only because the interviewer instructed me to do so ahead of time. Had he not given direction I would have worn a suit.