Just whatever for your own consumption, plus donate one item for the crowd. After we get a decent nose-count, we can work up a list of some extras to bring.
Also, I cannot pick up all the food & beer, but I can buy a few cases of beer, limited junk food, and some disposable coolers for others who can't bring there own due to their logistics.
I can't help there -- we stay with wife's family. If you stay near the airport, don't stay in mid-grade or economy hotels - it's a seedy area.:ref:
If you stay downtown or anywhere near the light rail, note that the tailgate location is a few blocks from Light Rail. Downtown Seattle has a bus tunnel -- free service in the deep downtown. It intersects with the Light Rail. Point is that you could have the option of not having to rent a car.