You can put in as many Chromis as you want they are pretty cool when they swim in a group, but with your size tank I'd go for no more then 2 buddy. You should get a Clown fish to, great fish and everyone loves a Nemo right lol. Everyone knocks Damsels but just like every animal it differs with every fish, I think anyways lol. I have two chromis', a clown fish, Yellow tail damsel and a blue damsel all in a 50 and they are all fine. They chase one another but its all harmless. the meanest fish I have is a lawnmower blenny and guess what, suppose to be friendly lol... and a coral beauty who also can have an attitude

My clown fish attacks me when I put my hand in the tank but he's great with the other fishes haha.
Anyways with this hobby I think its all about experiences, put whatever fish you like in your tank... chances are they will be fine, but you may have that one that just has a bad attitude, they are living animals after all. (And I dont mean to put Triggers in with damsels lol).
what's more important then what fish you put in your tank is the way you put them in. Always follow a good acclimation procedure when putting your fish in the tank, the drip method is the easiest on them, but any method that provides them oxygen and acclimates them over a period of time long enough to safely adjust to their new home is good.
Cheers!
Ian