I've currently got a five foot tank (5 x 2.5 x2.5) with 1 yellow, 1 sailfin, 1 blonde naso and 1 mimic tang and they all get on no problem. I also have a second tank (300litres) with a small kole yellow eye tang and a scopes tang, they also don't have any problems. I do have a lot of rock and the naso and mimic where added to the big tank when we moved, so for the tangs in the current set up they all went in at once. The naso is the biggest (about the size of your hand) and he is a girl, will hind from anything.
My new tank comes in two weeks (2200litres 10 foot x 3 foot x 2.3 foot) and all 6 of these guys will be going in together. I was thinking about two additional yellow tangs and two additional sailfins but I'm not sure (I do love my tangs and I want them to be as happy as they are now).
I also have a Flame Angel in my coral tank with no problems but we had a coral beauty in the second tank and it would eat anything ... I agree it is luck with these guys but I was also thinking about the lemon peel as they look so very nice.
I have school of five chromes in the big tank without a problem, if anything they really do stick together. I also have three cheaper anthias and they tend to stay with the chromes and the pink and blue look great. I was told that 20% of bartlett anthias will die, I don't know if this is correct however it is the reason I went for the cheap ones and I've never lost one of them.
I love the copper band butterfly fish and I had one, he went fine for six months. He was eating, never saw him pick at the corals however he just stopped eating one day. I tried everything I could but within two weeks he was gone.
Good luck, it sounds like you'll have a great tank.