I didn't upgrade or add to the bar options - but I know you can. I think there's a list of what is provided on the Adventure Weddings website, but I'm not sure, and not sure it shows the brand, if that's important to you.
Would you be going over early to Las Caletas that morning? I know they give the bride and her guests first dibs at the spa if you're interested - we didn't sign up for anything, but we were asked after we got on the boat. They ask all of the guests on the boat/day cruise at that time, but Nicole makes sure the bride and her group get first chance.
We gave the DJ a few CDs that we made with music we like - but we also said he can play what he wants. He did a mix of both. You can definitely tell him to only play off of your CD if you want to, or maybe just give him a "do not play" list - many couples do that.