It's a pretty laid back day. You'll have 3 interviews (30 minutes each) - mine was with 3 of the professors there but it could also be with some of the administration members. They ask typical interview questions "why DO" "why VCOM" along with hobbies or anything else on your application they found interesting.
I recommend getting there a little early and seeing who your interviewers are - they give you a schedule with all the applicants and who you will be interviewing with. Google them to see what contribution they make so that you can ask them questions about their research, field of study, etc.
The day starts off with a presentation about the school, then your interviews, then the tour of the building followed by lunch. After lunch, they do a tour of the facilities not located in the building and then a driving tour of blackburg/VT. After you get back, you'll get a short presentation on financial aid an a conclusion where they'll tell you when to expect to hear back by.
Everyone is super nice and welcoming but my experience was that after the 3 (sometimes back to back interviews), you're very drained. Just make sure you are good for that 1.5 hour period where you are interviewing!
Best of luck!