Pack for warm weather but aloow for cool eavnings.
I dont sneak mutch but I understand you can have alcohol delivered to your statroom.
There will be lots to do... but I have long forgotten what a late 20 something wants to do.. If you like to drink, you will be in good company, Thre will be a number of clubs on the ship for night life.
take a look at some of the photo albums. Youl get a good idea of what people are wearing... it's like a vacaion anywhere else.. casual comfortable cloths and bathing suites mostly.
Welcome to the board.. your gona love cruising.