The PVSA fine is per passenger.
Like with the OP, RCI will charge the credit card on file - hmmm, use a cash account to avoid any extra after cruise charges......where have I heard that before?
The availability of planner items doesn't usually change with cabin type - folks in a suite can still buy Voom (someone may want access for another device).
As long as the site doesn't get stuck when entering the credit card, you should be fine. The likely answer from RCI, if you ever get one, is to book in your home market only.