The trick is to set the app to the current sailing (not yours) and filter by Entertainment. Also, many ships don't have a "Broadway" show but one or two Production shows - Explorer is like that.
The provided remote turns the TV on - the trick is to switch the TV to the input where the Firestick is - the remote doesn't have an input button like your home remote.
The more you play the more you gain points. Enough points eventually turn into perks, like free cruise offers which you can look up here: https://www.clubroyaleoffers.com.
The way the question was posed, I assumed the poster was talking about being assigned a 4V - you can only move to another available cabin in the same exact category. There may have been some very spotty reporting on downgrades - that is probably very YMMV.
Just realize that the grats will still be added to your account during the sailing - so financially, there's no diff between pre-paying and paying later if you pay the standard grats amount. Now, if you want to remove the grats and tip in cash..............