Re: Island hopping between BVI and USVI?
Don't know about prepayment for a return to the BVI, but I do know that the US officials expect you to check in (e.g., at Cruz Bay) with Customs/Immigration when you come to the USVI and that you have to have everyone in your crew show up in person. When you go back to the BVI they only want the skipper to show up in person, but with passports for all.
BTW, you can tie up to the US customs pier, but they will charge you and you will have to get off the dock ASAP, because it can get very busy. I've done it and don't recommend it for the faint of heart because of the tight quarters and heavy traffic. After 15 minutes they practically pushed me off the pier to make room for other boats. At least the check in process was very fast compared to the BVI.
There is a very small anchorage in Cruz Bay, to your port as you enter, but you probably should pick up a mooring around Linde Pt, towards Caneel Bay, and dinghy in.