I have to disagree with the Tang. He may be small now, but can reach (if you plan to have him long term) a full 8-9". Also, even a small tang need a lot of swimming room to thrive which a 55 gallon does not provide.
I know its an old argument, but I have seen too many post about YT aggression and diseases and I have to believe a smaller tank does help lead to stress which can bring potential problems.
I've heard you need to be cautious with angels but a Coral Beauty will not really mess with corals from user posts off google I've searched. What about the flame angels?
Its a crap shoot with these fish. Sometimes they are fine with a reef, other times its "belly up to the buffet".
Any Centropyge has the potential to be a coral picker. You can try one, but be prepared to catch them. Impossible to tell until you get them home.