The tank will be too small for the Blue tang (hepatus). Good to get it as a juvenile. Some are known to eat coral, but less likely to if you get as a juvenile and feed it good with meaty food. Purple firefish good, just make sure you have a top on the tank (they jump) and must have a mated pair. The bicolored blenny is generally a good choice, but is known to nip at large polyp stony corals and clams when hungry. They may also nip at the firefish.
Perculas are the good all around choice.
Perculas are the good all around choice.