If he does not come back to answer these, I can at least help out a little, having stayed at HV recently. I only did shore diving, so I know nothing of their boat of DM situation.
Gear storage is in room full of good sized cubby holes, which is open during the day and locked up when the dive shop closes (5 or 6pm). The resort is gated, and I did not have any concerns about somebody walking off with our gear. If you want to dive outside of the hours the shop is operating, you just have to plan ahead and grab your gear, and keep it with you until you can return it to the locker. Tanks are readily available at the dive shop and at the bellman's desk by the front gate (when the dive staff remembers to replenish this supply, but we only had to wait for tanks up front once during the week).
For shore diving at the resort, the shop is at the Eden beach/north side of the resort, and has a beach entry or dock entry to go up and access the north side reefs (Front porch, i think?). There are also carts available to transport your gear to the other end of the resort (town/south side) so that you can do a beach entry and dive those reefs (something special?). There is a sailboat wreck at the resort and some established as well as newly planted coral, but overall it is not as nice as other sites on the island. You can also use the carts to move your gear/tanks from the shop to your truck outside of the gate.
The only aspect of the review above that I disagree with is the quality of the on-site restaurant. The food was just OK at best, and very overpriced, and the options in town (15 to 20 minute walk) or next door at Eden Beach or Between2Buns were much, much better. I loved everything else about the resort, rooms, beach, location, etc. and will stay there again when we return.