captboob.......my favorite place to dive.......probably because my aunt-in-law lives in Frederiksted on a beach and have been visiting her every few years since 2005.
In early April the water is 79-80; by late June it can be as high as 84, so I would say expect about 81-82 degrees. Last dove in December 2012, water was 84.
Water on west side (Frederiksted) is calmer than water on north and east side. Walls: on north side, Cane Bay, which is a shore dive and has beach, snorkeling, and good place to eat; also on north side, Salt River Bay also has submarine canyons.
Best shore and night dive is Frederiksted Pier. Seahorses, frogfish, and many other critters come out at night.
The dive shop to go with in Frederiksted is N2theBlue. They are about a football field walk from the pier. Pick up a tank from them (they let us use their cart) and do pier as shore dive. Of course they will guide you also. We always jump off the pier on one side to enter and come up at a little wooden dock on the other side.
N2theBlue's boat dives leave from the pier also. Short rides to dive sites and great people. They also do other night dives. There is a small parking lot by the shop.
Car rental has been pretty easy and different. We pick up car at airport and then drive to an auto repair garage (I think we rent from Midwest Auto) to pay. Have only had one problem with a car which was remedied. Remember to drive on the left.
A couple of FYI's if interested: the only USVI casino is at Divi Carina on southeast end of island....okay if your into that; 1844 Tavern (in Christiansted) has the best (I never say that about anything) hamburgers from Greg Norman raised beef; and there is a snorkel trip that leaves Christiansted and goes to Buck Island Reef which is a protected national monument...nice to do one time.
If you have any questions about anything, I'll be happy to try and answer them.
Jon
we will use it. 
