According to Princess' website, you can not only order a bottle of wine for stateroom consumption but you can bring your own onboard as well.
You will only be charged the corkage fee if you have the wine in the dining rooms.
Smart Casual in the Caribbean = khakis/chinos and a golf-style shirt for the men, my hubby wore casual pants and a dress shirt and tie and was also not out of place. For the ladies, a nice sundress or smart pant outfit is nice. Just please no jeans, shorts or t-shirts.
You will definately be able to get a taxi in St. Thomas. We didn't make it 5 feet without taxi drivers offering us their services.