Why the Sixline Wrasse? Just curious? A lot of people have issues with them being aggressive (I certainly did) so if you do decide on this fish, put it towards the end of the stock list.
Since your tank is really too small for a Tang, you might want to consider a dwarf angle such as a Coral Beauty or Flame Angel. Just a thought.
As for Gobies, are you looking for one that is a sand sifter?
4 firefish and 2 wrasses - you know these fish are KNOWN jumpers, yes?
Have you considered a quarantine tank? You really should have one, even a ten gallon would be okay, but I prefer 20G. I may actually have one that I can mail to you (I have no idea what the shipping is), my zip code is 11763 if you want to look it up.
As for a CUC, I've since learned that hermits and snails, no matter what you do, usually don't mix. I've decided that when I move my 155 to a bigger tank, I'm getting rid of whatever hermits I have left. They just kill the snails, even if I add shells for them. I think they enjoy killing the snails for the shell. I HIGHLY suggest you get about 10 nassarius snails, 10 trochus, 10 ceriths and 10 astreas. 2 cleaner shrimp, 2 peppermint shrimp (not necessary, but I like that they MAY eat aiptasia), 2 Emerald crabs (don't over do the crabs or they'll starve and/or fight with each other)
I'd write more, but it's getting late.
Glad to see that you decided to go with a sump!
Good luck.
