The shows---the "guest" performers are top-notch...the "production shows"...not a fan...they're good enough, I suppose, but I just don't like the "no plot" glitz"....personal opinion.
The "hot tubs" are all fresh, treated water. The pool are salt, on Voyager class and below. Freedom class are fresh, treated pools.
Excursions... do some research on your ports. A guidebook is a must. That way, you'll know what is available and if it's doable on your own. Things like beaches, shopping and just walking are usually EASY and cheap to do by yourself. There's no reason to pay those prices to go to a beach, when a cab fare will do the same thing! RESEARCH!!!!
Adult learning....who cares? On vacation, I really don't want to learn anything more than if one Vodka tastes better than another!!! (They do have some "learning" experiences...I've just never taken part!!!)
On RCI, you'll get great service, so-so food, and alot of fun....and, it's a lot cheaper than Disney!
Good luck and have fun!