Having been through several direct hits here, the recovery after one of these things is always much worse than the storm. Good luck on the recovery. I hope your insurance rules are better than the ones we had in the Bahamas. Those rules insured against everything except what you could could actually have a claim for.
As far as the washed out dive shop is concerned, if there is rough hard bottom off the shore there most of the "heavy bits" will be sorted into that area. If it's a thick sand bottom there is a good chance the heavy bits will be under sand. If you want to help the shop a few "trolling dives" where the divers are dragged behind a boat in a search pattern may recover a fair amout of the lost hardware, specifically the bank tanks, filters, and compressor head. If submerged for less than a couple weeks they all should be salvageable. Tanks will be recoverable up to a month if the valve broke off and the inside flooded, up to several months if the valves remained intact.
If there was a signficant angle to the wave action the debris may be "downcurrent" quite a ways. A weather station washed off a pier in Lake Worth Fla in the hallowen storm (the one the movie "Prefect Storm" was about) was found intact about a half mile away in 30' of water several months later. "Soft" bottom is liquified by the wave induced shear forces near the bottom. Heavy bits sink through this soup quite readily. One oil rig lost in Camille was located upright in the same location by seismic surveay, withthe top deck 80' below mudline. The bottom simply had liquified to below the piling depth and the thing 'sank' into the bottom. Because of this your best bet for finding the gear will be in the depressions among and between the reef lines. Debris dropped into those will generally not be lifted out again, and liquification will be minimal in those areas.
Once again I wish yo well through the recovery. Most folks who havn't been through this a few times don't realise that you are on your own for at least a couple weeks, as help and spare parts takes a while to make it to an island.
FT