There will be no problem with food or luggage having to be declared,taxed or inspected. Only the Captain needs to appear at BVI Customs with all the forms and passports.
When you clear back into the USVI all persons must be present at the C&I.

pueblo is Sub Base will certainly be more than adequate for provisioning - if you have a large group Cost-u-less can be a viable alternative but I will say Sat. afternoons there are a bit of a crowd. Gourmet Gallery in Crown Bay is close to Pueblo if you want to fill in some holes on the list for more specialty items.
Christmas Cove on Great St. James is a good overnight coming back and probably an hour or so from the CYOA base. You can check it out on the way out from STT the 1st day and get a better idea.
I see the CYOA boats almost every day on their docks and they keep them up and clean and ready - they will certainly give you any guidance on the mainsail and the boat overall.

Frenchtown has plenty of interesting food and drink options steps from the docks and Hook, Line Sinker welcomes the CYOA sailors and staff like a clubhouse.