I am totally clueless to this whole wedding industry thing! But happy to suddenly be plunged in the middle of it!

So does anyone have any advise on what to expect to pay for catering?!?! If we have a salad course + an entree for a 100 person reception, what should I plan on budgeting per head? (not including Cake costs- assuming my cake provider is separate, they are a separete service / line item right???) See what I mean... CLUELESS!!!

HELP! Thanks ladies...