You want to think tailgate style for this one (google tailgate for more).
Consider gas grills, crockpots and/or even a deep fryer. Don't forget garbage bags, plastic platters and big bowls. You may want to bring pails for dirty dishes if you will rack them up even using paper products. Chests of endless ice are almost always key, no matter if you're bringing stuff cooked or preparing it the night before and bringing it raw.
Food, I guess it all depends on how how sophisticated you're wanting to go... or how many people are contributing. You can make almost anything, so it just depends on money/tools available, how much you're willing to work, and if anyone can trade off/man grills.
For the breakfast you can make a ton of boiled eggs ahead of time, buy croissants by the box, also consider muffins, tomatoes, sausage, fruit salad things that "go" with bfast or even set up a bloody mary bar, bagel bar or other kind of bar if you have experience with that.
For dinners, some things I like for preparing en masse include: salad, shrimp, pans of ziti (and the like), clams, pans of a "side" (could even buy those frozen potato cuts) red beans and rice, gumbo, cornbread (or similar), drunken kielbasa, brownies, chicken wings (even pre-sauced frozen wings), chili, potato salad, slaws (of all kinds), subs, sheet cake...
Of course silverware, dinner rolls, fruit, olive mixes, etc go a long way.
Quesadillas can be made ahead of time and tend to be a hit. I've made 100 chicken quesadillas at a time, with shredded cheddar, broccoli bits, diced onion and jalepeno (buy the tall, cheap stacks of white burritos, fill em up, stove-top them and slice into quarters. I'll admit they're better hot, but fine and make more sense cold (they're very small and people will eat like 4+ each even with other food).