Agree that the blue tang gets too big for that tank, but the yellow would work.
For the CUC, I like astrea snails, banded trochus, conch, Nassarius snails and scarlet reef hermits. I would say about 25-30 Nassarius, and 25-30 total of other small snails. If you get turbos, you'll need far fewer than that. 2 conchs would be about all you'd need. And maybe 15-20 hermits. Don't add all of this at once, though. There won't be enough food yet and they'll die. Start with matbe 1/4 of that.
Cleaner shrimp are super cool. You can get an emerald or ruby crab, but I don't like my ruby for various reasons, and I rarely see it, so it's not much fun.
Congrats on the new tank!!