Adding tankmates

I'd like to add some fish to my current 90 gallon FO (sort of) WLR setup, and I was hoping to get some input from the group as to what would be good to put in with my current stock. The current line up is:

Diamond goby
2 clowns
Powder brown tang.
1 Featherduster
1 zoa colony
Snails: 2 turbos and a ton of nassarius.

I used to have 2 emerald crabs, but I'm afraid the goby might have buried them. I haven't seen them for a couple of months.

I'm planning on setting up a small (40g) reef tank in the near future, so I'll probably move the zoas to that.

I'd like to add at least a Flame hawkfish, a yellow coris wrasse, and possibly a dwarf angel of some sort (preferably bicolor, potters, or rusty). I'd like to add another tang, but I'm afraid that wouldn't go over well with the powder brown at this point.

I have fairly extensive rock work in the tank, but I intend to add to it when I add more fish to diminish some of the territorial squabbling that is sure to take place.

I know I'll need to do my own research on this, but I thought I would check with the group to see if anyone has any recommendations or preferences.
The more I look at the potters, the more I like it.

The clarion is pretty. Even if I could afford one, my tank is too small. I'm also reading that they are considered to be an endangered species on some watch lists due to their limited range, but it looks like people are having some success with captive breeding.