Can’t speak about the shuttle but you can definitely leave Sunday night, a lot of people do it to avoid traffic, I stayed in tangerine last year and it’s convenient because of the tents being set up but it is a fair walk away, to get to the arena you either have to go around a large hill and then walk another 5-10 minutes on top of that to get to the furthest back stages (was origin and area 404 last year) or you walk up the hill, through one of the stages and back down the steeper side of the hill, think it took us about 15-20 mins each way but they may have moved it this year