Crabs and Snails

depends on if you want a reef, fowler, mixed and what kind of fish you're planning on stocking.

Well, the hawk will love crustaceans not sure if it will eat hermits but, shrimp are high on it's menu. I don't know what sort of lights you'll have but, if it's normal out put I'd get about 30 narcisus snails, 10 turbo's for algae controle ,"you might have to feed them or add more if you have more light", 3 or 4 serphant stars and a tiger tail cucumber to keep the sand bed clean. You might also add 10-15 red reef crabs but, I'm not sure if the hawk would eat them or not.
hth
chris