No - they don't charge for any of the shows. Only the dinner reservations were charged.
NCL will be charging for entrance to some of their nightclubs when Epic debuts, but I doubt they will take reservations online for that.
I admit I was a bit surprised by the dinner being charged to my vard right away. I thought the credit card would just "hold" my reservation, but they actually charged my card. I saw the charge on my statement.