You'll probably want to get the angel first. IME, yellows are more aggressive than most dwarf angels, and will beat the heck out of them if the angel is added after the tang.
Yellows are mostly reef safe. If they are well fed, they may nip at a few corals, but usually leave them alone after an initial taste. If they are not fed properly, they have been known to go after the fleshy mantels on clams, and some of the non-toxic soft corals.