(I'm avoiding work, so this will probably be LONG!) I don't remember there being any really decent food options IN the campground. There's one shack that sells some pre-packaged stuff, but it's less well stocked than your average gas station and not really an option for more than batteries and bottled water. It's always been my understanding that once your car is IN the campgrounds, you can't leave. But I had a friend who was staying in the "premiere" camping portion last year who had a pass giving her in-and-out priviledges. But honestly, I don't think it would be worth it. The campground arrival/set up process is madness...with lines of cars for seemingly miles. Expect to be without a car once you're parked. Bring a cooler and groceries with you. If you're in the general camping area, be prepared! It can be total madness, but also great fun. If you want to sleep earlier and/or have a hard time sleeping with noise, bring earplugs. People stay up drinking and partying ALL NIGHT LONG! Also, the porta-potty situation can be downright HORRIBLE later into the festival. It's okay in the beginning, but they begin to fill up and then OVERFLOW as the days go by...honestly not sure how people are still using them...squatting over the hole, I guess. So yeah, just be prepared for that!
The campground is just this giant field, and everyone parks next to each other and then the area right behind your car is your "camp site." So bringing some folding chairs and/or table is always nice. A blanket or such. There are no traditional campground amenities. And bring good shoes...there's lots of walking and sometimes broken glass around. SUNSCREEN! And water bottles. The ampitheatre has all kinds of restrictions on what liquid you can bring in. But I think you can still bring in pre-sealed water bottles...so get a big one (1 liter) for each person for each day, and then they do have refilling stations inside the music grounds. Also, bring layers. It's generally crazy hot in the day, but after sunset can get chilly. Plus, if you've had too much sun, it can be nice to have a zip-up hoodie to hide under. In years past, the campground has hit capacity before the concert even starts...which is horrible! This year it looks like you MUST HAVE A SASQUATCH TICKET for each person in your car to enter the campgrounds. This seems like a decent solution to the problem of too many people showing up for the all-night parties.
There are some decent tips/information about how this year is working here: http://www.gorgecamping.com/SASQUATCH-2011.html
There is another privately run campground called something like Wild Horse a little bit outside of the Gorge. I have no idea how the pricing works, but when driving past, I've noticed nicer tents (even some RVs) and a more reserved attitude there. They MIGHT still have reservations available...but it'll be pretty expensive.
The other option is to upgrade to "premier" campground at the official gorge campsite. I stayed in Premiere once. It's ok, but not as amazing as they make it sound. It is a bit quieter, and there are "real" toilets and "real" showers. They park these two plumbed trailers. But the lines for the showers and toilets were always INSANE. And the toilets would still plug up and not work right. OH, BRING TOILET PAPER and hand sanitizer. They run out of that, as well. So is $160 worth being a bit quieter (the all night partiers will be 30 feet away rather than surrounding you) worth it?
Within the festival/concert grounds, there are several food options. It's not the cheapest, but the variety has gotten a bit better...in addition to burgers and hot dogs there are some wraps. It's still stadium food, but an option. But you can pack your own food. Bring blankets/towels to sit upon...I always like to bring a pillow, as well. There's no re-entry during the day, so remember to bring EVERYTHING with you each morning. Oh, and bring a flashlight too. It gets crazy dark at night and trying to find your campsite can be treacherous. Please look for really good markers/location identifiers for your car/tent so that you can find it again. After all day rockin' out, it can be way hard to find in the pitch black. Cell phone service is spotty at best, depending on your carrier, so know that meeting up with friends just using your phone may not always work. Picking an agreed upon meeting location/time can help, too.
This livenation link has venue rules and tips...on the righthand side, scroll down. http://www.livenation.com/Gorge-Amphitheatre-tickets-George/venue/122913