I would keep one angel, two might be too much. AS far as another tang, well, thats' subjective. Me, I wouldn't do it but I'm sure plenty of others would.
I would wait awhile though either way, you just put this tank together a few weeks ago and I would wait and see how the water parameters are before adding more livestock. You already have some messy eaters and big poopers. LOL
My blue tang by the way is a real sweetie, he's a big mush and not at all aggressive so not too sure how well he would do with your aggressive fish. Yellows are alot more aggressive and sure of themselves so that might be an option.
180g- Mostly BIG fish and some coral. ~80g Nuvo- My coral tank with "happy fish"~ 90g- FOWLR Not the not happy type of fish~ 125g- Freshwater Malawi Cichlids ~10g- Nuvo- The refugees from the Ich of '18