I think you'll be fine with both tangs. I have 2 yellows, a pacific sailfin, and a bariene tang in my 187 gallon. I still plan on adding a powder blue tang.
I would skip the chromis though, I had a big group and they killed each other off. Look into fairy wrasses, as well as the melanurus wrasse (I love my melanurus). I have had good luck with odd numbered groups of yellow tailed blue damsels in my tank. I currently have 3, along with a blue devil (started with 5 of these, 1 killed all the others, but leaves the yellow tailed blues alone). They get along fine with all the other fish.