What should you know? Unlike some Caribbean cruises, you need a passport. There is not time now to get one (average processing time is currently 13 weeks).
While it is a
Disney cruise, it really is different than the Caribbean (for many, a very lovely different). You still get shows, movies, youth clubs. Characters in AK costumes are fun.
But excursions can be pricey. You do not have to do an expensive activity in every port, but it can be tempting. There is no port where you get off the ship and have a long, cheap day at the beach. Most ports are easily walkable!
You can go all week and have no sun. It may rain a lot. Or not. Early sunrise. Late sunset. Bring a clip to keep curtains closed if not in an inside stateroom.
Airfare to and hotels in Vancouver are more expensive than Florida.
(I am definitely not trying to discourage you; AK is my favorite cruise destination. I’ve gone 5 times, only once on Disney).