First off welcome aboard.
I do not see anything about you running a sump, is there one with the system?
As for fish you are going to want to get rid of those damsels, they are pests and will cause you nothing but problems with their aggressiveness in the future. You can add all kinds of fish with a 125g tank, most tangs will be good in there, rabbitfish, wrasses, anthias, and more. Your best bet is to go to liveaquaria and look through all their fish and see what peaks your interests and read about those fish. But if you want a reef tank, stay away from the large angels and triggers their are a few exceptions but for the most part they are not reef safe.