My Research Notes for Bonaire -
My Research Note For Bonaire
You might find some useful info., including on shore entries. Dead coral pellets can slide under your feet a bit. The step-off into the sea can be a bit much; I know of a YouTube series guiding people on shore diving where they mentioned foldable walking stick use to help with balance.
Personally, I wouldn't worry about having oxygen at the dive sites. Everyone has to make his own risk tolerance judgment calls. New divers are unlikely to do very aggressive diving and/or need it. Granted, 'not likely' doesn't = 'it cannot happen.'
Due to risk of thieves going through your truck while you guys are down, it's advisable to leave nothing in the truck of substantial value (extra tanks are okay), and leave doors unlocked and windows down (so they don't break in).
While you can buy medicine at a pharmacy, don't expect 24/7 Walmart Super Center type access. I take a personal 'medicine cabinet' - triple antibiotic ointment for abrasions, the pill form (generic) like Pepto Bismol, Imodium, Sudafed (the real stuff, pseudoephedrine - to aid ear clearing), Ibuprofen, Flonase, Claritin and whatever else I think I might need. A swimmers ear preventive I buy at Walmart to use every few dives (prevent swimmer's ear!).
Thick soled dive boots may save you some foot pain.