Having lived in Madison for 17 year I feel that I should have some input here. As far as State Street, other than buses and deliveries, traffic is never allowed on the street. Lots of bars, lots of people, there will always be a lot going on if you visit State Street (not as much as Halloween, but that's a good thing!) I'm told that there are also a lot of good bars on Regent Street.
Tailgating will be going on ALL around the stadium. A lot of people park a long ways away and walk to the stadium (we rent out my high school parking lot for parking). I'll post more info as I talk to my friends that attend/live in Madison still.
Getting cheap tickets, especially for that game will probably be very close to impossible... as may be getting tickets at all. Make sure you check out the new "monument" (I guess that is what they call it) right by the stadium... a lot of people find it really amusing Jump around is definatly an experience, as is the entire student section. And the great part about it is that the rest of the stadium loves it, football is the way of live in Madison and Wisconsin in general.
Hopefully this helps some, let me know if you have any other questions and I'll see what I can find.