I was there to see Primus last summer. It's all GA. No seats. It's basically a pier on the water. There was 3 or 4 booths in the back to buy food (cheesesteaks), merch or drinks and one tent where you can buy alcohol. It's not covered - all open air (except the tent).
I'm getting to the Oasis show early since it's sold out and I'm sure the crowd will be much bigger than the Primus show was. Parking is right next to the venue. I don't know how much it costs since I stayed at a hotel last time, but bring $5 to $8 to play it safe. There's also a restaurant or two on the water within a half-mile in case you get there early. We saw a Primus soundcheck that way.
It rained at the Primus concert and everyone was getting splashed by people jumping to the music.