Once paid are you able to leave the park and come back in without having to pay again?

Tes

I would hope you would be able to get back in if paid for the day

I'm not certain of theory policy but when you pay you receive a receipt, so I would think that would be sufficient for re-entry.

I don't know how they would track who comes and goes. If you have a state Park pass you would be all set to come and go. You can always call and ask.

I think so, but I avoid it because it gets crowded and very buggy

Not quite sure of that, as I usually use the companies state pass