We booked the catamaran through sunwing, the boat was in really good shape just the nets looked sketchy. There was a couple similar boats in the marina, I guess we just lucked out and got the "good" one
Ditto on the duty free but keep in mind the cigar selection is fairly poor so if you want something specific better to buy in town or at the resort. I didn't notice a huge price difference with cigars, but yes a few bucks cheaper for the rum.