Check out the Culebra Cruisers and Boaters group on Facebook, it has good info and Sue the moderator lives on island.

General info on customs, decals, moorings, laundromat... - https://www.facebook.com/groups/culebracruisers/permalink/1150813048268122/

Here's more info from a recent post regarding groceries:

Milka's is great for general provisions, onsite butcher for churrasco and ground beef, chicken and provisions. There is a dinghy dock behind them on the canal.

There might be some more exotic cheeses and artisan bread at El Eden. Fresh veggies at the veggie market several days a week and at D's Garden (on Facebook), likewise. Extensive selection of frozen and canned goods, as well as OTC meds at Suprette Mayra. Prices are the lowest at Costa del Sol, near the airport with somewhat limited selection.

Note: Cost del Sol is where the Flamenco Beach campers do most of their provisioning. El Eden has a bigger liquor selection than Milka.

Cheers, RickG