The diff is that Enchantment is still sailing while Ectasy is being dismantled on a beach in Turkey. Seriously, read some Enchantment threads - pull down menu on the main RCI page here at CC.
The kids may appreciate a second Flowrider and you'd appreciate the $2K savings going on Harmony - no real diff between them other than the new car smell.
This may vary by ship, date, venue and kind of booking (free or paid). The free ones can only be booked on board but some paid ones will likely will also be available.
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.