Do they close down any roads around the stadium on game days? If so, which ones, and any idea when they close them down?
I know that Ann Arbor-Saline is southbound only toward I-94 following the game. Outside of that, I'm not aware that they close any roads.
And please remember, the legal drinking age is 21.
No they don't close any roads, but traffic around the stadium will be bad (pretty obvious there). However after the game Ann Arbor-Saline is Southbound only until I-94
Is not shut down, but please don't be that guy trying to drive down it 30 minutes before kick off.
Never goes to fail, though, that someone tries to do that every game.
State Street is effectively closed in the sense you do not want to drive on it, same with Main. Basically try to stay one major road away from the stadium (as in: State Street bad, South Industrial passable).
Aside from the restrictions on Ann Arbor-Saline Road which have been mentioned already, nothing is "closed" except in as much as the flood of vehicles serve as an effective barrier prohibiting late-arriving (and late-departing) traffic from proceeding quickly.