For this many people, unless you are a Rockerfeller or plan to rent a tent and furniture
my advice to you is heavy heavy hors d'ourves, something big and meaty like a ham - I like the idea of buns and fun mustards - and something starchy (go for the potatoes!!). I did a birthday party for 72 once, yes, I counted! People were spilling out all over the place, it was mayhem and great fun! I had two huge tables filled with food and a separate table for desserts, oh and 3 bars! The kids had a corner all to themselves and that was just fine. After the party, I had the carpet cleaned and furniture cleaned and since it was my (ex)boyfriends house decided not to repaint. How does one spill red paint down the walls??!!
Anyway, your menu sounds great, just make it easy on yourself, don't worry about people sitting to eat, and don't forget the party hats and noisemakers for midnight! wish I could come!