Help with 28 gallon biorb

I just set up my first salt tank in a 28 gallon biorb, no sand just about 25 lbs of live rock, and after cycling pair O.clownfish, 2 damsels, a cleaner and a firecracker shrimp, various hermit crabs, snails, snail-looking things and baby starfish that came as hitch-hikers. Oh and some zoanthids and mushroom corals. I added tigger pods and brine shrimp but who knows how many survived the damsels. I'm using the lights and filters that came with the tank. Ammonia and nitrites zero. Been running for 2 weeks. So....

1. How often and what to feed, add to water?

2. Water changes?

3. Any more equipment needed?

4. What else do I need to test for?

5. Can I add 3 chromis? 5?

Any info will help the impending doom I feel will surely descend soon.