Re: Bvi - usvi- svi
Checking in at JVD can take 30-45 minutes, including filling out forms and allowing for one or two boats ahead of you. The skipper alone shows up with passports, ships papers, and money for the cruising and park permits. You tell them how long you will be in the BVI and they charge you accordingly.
When we checked in at Spanish Town it took longer, but maybe the procedures have changed overall in the BVI. I ended up going back to the boat to get individual forms signed by everyone. That process took an hour and there was no one ahead in line. My impression was that they didn't see many US charters check in there. I'd allow an hour here.
When you check back into the US, everyone has to show up in person. The process is relatively quick, as they process lots of folks from the excursion boats and are used to keeping things moving. Just be sure you are not importing agricultural products that you might have picked up in the BVI. This includes Washington state apples you bought in Spanish Town! Allow 15 minutes at customs and there is no fee unless you tied up at the customs dock. We paid about $26 for a 42 ft boat and they pushed us off within 20 minutes to make room for the parade of excursion boats.
As far as locking the dinghy goes, I've heard that it is increasingly recommended in the populated areas in particular, like Cruz Bay. Otherwise, I wouldn't worry. The charter company has your deposit, just in case, so its your call.