Book early! Most hotels will jack up their rates and probably insist on 2 night minimum.
Many will just drive up and back, and make Annapolis their HQ. If you want the downtown Baltimore experience Friday night (A-N Boxing Smoker!) and before and after the game, walking around, book near the Baltimore Convention Center/stadium.
Plenty of interesting neighborhoods and both local and mid-range/upscale chain restaurants, plus requisite crab cake places. Reservations will be key. Little Italy is fun. Walkable, extended, from convention center area. Fells Point used to be a dive bar area but has now been gentrified and revitalized with trendy places. Remember it will be December, and there could be a nasty, damp wind off the harbor.
In Open Table, neighborhoods to check, walkable or short drive from Inner Harbor/Conv Ctr:
Downtown
Harbor East
Federal Hill
Fells Point
Little Italy
There are certainly more areas to explore, but in the next ring of neighborhoods surrounding the harbor.
There are plenty of gastro pubs and casual fare places - Yelp will be helpful.
Check Diners, Drive Ins and Dives locations on Food Channel website. Guy Fieri has been to Charm City several times.
Favorites we visit regularly, more because we are local, and it's something different from home in Annapolis:
Cinghiale
http://www.cgeno.com
Petit Louis Bistro
http://www.petitlouis.com/mobile.cfm
Charleston
http://www.charlestonrestaurant.com/mobile.cfm
This one is serious dollars. I included it for variety, and it is worth it.
Top things to do we steer our visitors to:
National Aquarium (Inner Harbor)
USS CONSTELLATION tour (Inner Z Harbor)
Ft. McHenry
Transport: Much will depend if your mid is returning to Annapolis after the game. Plebes usually do, via the buses, unless an unexpected overnight is given. No way to tell at this point. There are no stadium parking lots for general ticket holders. There are private lots surrounding the stadium, and game day parking is a royal PITA. If you want to go lean and mean, taxi/uber to hotel and forget a rental car, walk everywhere.