Yeah, a lot of this depends on your age and your drinking libido.
I drink a lot on holiday, cans of lager, but I'm 44yo now and so I can't do it every night, I certainly have no interest in day-drinking. I DO like the barista coffees though, and Odyssey is particularly easy to access them, especially as there is one in Windjammer, whereas on Symphony there is not so many places, so I drank less barista coffee and fresh OJ.
I probably have to drink 9 speciality drinks a day to break even on the package, so if I was you I'd cancel both and pay per drink.
But if he's wedded to the idea of the package, like my wife is, then we both get dragged into it.
Yes you can rebook at any time, provided you're doing it direct with RC and not through an agent. Might even be ok with agent, might not though.