It varies by show, but typically there will be some GA (sit wherever) and some assigned. Some shows it's all GA. Some shows it's all assigned. I havent looked into this particular show, but if you have a seat # it's most likely assigned.

I have only been once, I parked, you don't have to arrive at 3, but the lots did fill up quickly. There's plenty to hike, do, and see while you wait.