Hiya,
I rotated there last October. Advice . . . according to many of the residents, you don't really have to take that much call. One resident told me he took one night, others two. I think I took 3-4 the whole month I was there. You want to take call with the 2 chiefs that are actually on the admissions committee. Ask around and you'll find out who they are.
As for what to do there? Ummm, don't really know. I did 4, one week rotations and didn't really get asked all that much stuff. It was weird. Also since you don't take much call, I got to work out pretty much everyday. Tell Dr. Azar that you really want to go there and you may get an interview even with suboptimal numbers . . . I know one guy from UT-Southwestern who did just that.
Any other specific questions, ask away.