Hey tyshdogg,
I interviewed last March (didn't send my secondary in until December--oops) and in my group of 15-20, all but one were WI residents. I think they interview most qualified WI residents; the consensus from interviewfeedback.com was that UW now interviews a huge number of people overall, which is a change in their admissions methods. I'm not sure about getting an interview before completing the secondary, though.
My stats were 3.2/34, one year out of school working in a biotech company. The main things that kept me out, judging by the interviewers' emphasis on them, were several low grades (in science and engineering classes) and a lack of health care experience (I wasn't a premed so my extracurricular's weren't in health care). I'm trying to right those things and get in this year--Wisconsin was the only school to give me a good look last year, so you can understand why I'm anxious that they're the ONLY school I haven't heard from.
Best of luck to you, tyshdogg!