IMHO UW Madison along with UM-TC have priced themselves out of the market for Midwestern publics. Both are good schools, but they aren't at Michigan's level while they are trying to charge Michigan prices. They are more on the level of OSU, Indiana and Purdue which are all going to be significantly cheaper moving forward. Plus these three schools and others are much more likely to offer merit aid for top students than UW or MU-TC.
I would recommend you do the same thing my freshman roommate did the first day or two of moving in. He informed me he was gay, and we had a conversation about the ground rules of living together (which is something all roommates should have). I did not have a problem with it and we got along well. He ended up moving off campus after one semester, and, as far as I can tell, he didn't have any issues in the dorm with his sexual orientation even though it was well known. This was 30 years ago BTW.
In any case, it is relatively easy to change roommates in the first week of a semester as there are always people looking for a change. After the first week, it becomes more difficult. Just be upfront about what you expect from a roommate, and don't be judgmental about him.