CC stars are predatory and not reef safe. They can and will eat snails, corals, clams, etc....however, they can be spot fed, which makes them quite handy in most tanks. They are good scavengers, but should be spot fed. SOme people have no encounters with them eating stuff, but it is a risk.
I really do not recommend any Linckia, and certainly not Fromia (reef safe stars) for this tank. If it was a very mature reef tank with loads of LR, a Linckia multiflora is a possibility...but not until the tank is at least 6 months old with pristine water conditions. These stars can not be spot fed and most will starve in smaller tanks.
Ditto for sand sifter stars.
Brittlestars are an option.
But the best is probably a chocolate chip or general star, but the tank should still be quite mature as they are very senstive to poor water conditions. Also, they all need long acclimations, which is something to read up on when the time draws closer.