Dragon faces do fine in a reef, but they're super hard to feed due to their small snouts, so weaning them while they're in QT is practically a must. They actually do OK with Euphyllia, but I'd avoid any large Rhodactis sp. 'shrooms or carpet 'nems...you get the idea.
Flagfins do super well in reef setups, but for your size tank, blue-stripes would be best. One thing about blue-stripes: you MUST have a M-F pair...males will fight to the death, esp. in a smaller setup.