It's been a while since I've had the pleasure of tailgating at a U of M game.

However, from what I remember, there was no pay money and they'll give you food and drink situation. Most people bring there own. Lots of students who live in the houses around the stadium open up their lawns and charge money to park (less than the stadium) and you just hang out and eat/drink there. As long as you are not causing a rucus you should have no problem. Saturdays at the Big House are a site to behold, that's for sure! Have fun!
On the OSU front, my friend's boyfriend came to town from England a while back. Her Ohio relatives came up to visit, too, and brought him an OSU sweatshirt. He wore it on the trip back to the UK. At the Detroit airport security, the guard said "Full body cavity search for this one!" The boyfriend said "WHY?!?!?" The guard said "Standard procedure for anyone wearing an Ohio State shirt!"