Six Flags destroyed the place to the point where they still have bad attendance problems. It's going to take a long time for Cedar Fair to continue getting it out of the crapper.
I think it varies widely. Six Flags generally allows it but SFKK was not. PKI usually allows it, and seat poaching*, but sometimes not.
*Seat poaching is when theres someone waiting for your row, but you get out and take an empty seat after it loads.
No rerides is a standard Cedar Fair policy. I encountered it at SFKK as well. It's annoying sure, but not that big of a deal.
No cameras in line is just plain dumb. I would have filed a complaint.