Some boats supply air cylinders and weights, some do not. The dive supervisor is on the boat, you do not dive with a divemaster. Briefings explain the terrain and conditions, you and your partner dive based on your abilities. If a problem exists, wave for help. Work in and out of your gearbag, and always be sure your cylinder is secured.
Some boats sell food and beverages, some have food and beverages included in the price of the trip.
Some include airfills, others charge for airfills. It is customary to tip the crew at the end of a trip, when settling your galley bill. There is enough time to make 3, or sometimes 4 dives. These trips will go to a further out island. Multiple day trips will depart at night, generally go to further out islands for the first days of the trip, and work their way back.