It depends which field of ortho you're doing your AI in, as UPitt is pretty compartmentalized. I did sports med, and I think my experience was pretty different from the students doing trauma.
For sports med, you get assigned to an attending, and shadow him/her in clinic 2-3 days/week at the UPMC Sports Med Center, and go to the ORs at the nearby hospital 2 days/week. Both are on the South Side, but you're expected to be at trauma conference every day at 6:30 am (inc. Saturdays) and that's at UPMC on the North Side.
You have to find your own housing, I did so by mass e-mail to the entire UPitt med school. I lived near UPMC and it worked out well, as you can always get a ride with one of the residents to the Sports Med Center and your overnight call will be at UPMC. As for call. you and the other students make your own call schedule, with the condition that there must be one student on call per night. When I was there there were seven students or so, so I did 4-5 call nights. Call is pretty rough, I was up all night all nights but one.