Ok. so 20 gallons
I'm thinking you could get away with a flasher wrasse
Certainly a hawkfish (love them) you may lose some snails though (i'm not bothered by that, as I adore them)
Yes, a goby (go for a small one)
Not so sure here, but with good maintance - can also be a bit hit and miss on reef safetyness
Bi colour blenny (Bens favourite) yes, as long as you dont have the goby
So are you thinking - your all over swimming fish: a flasher
jumping about all over the rocks: Hawkfish
and for the bottom the Blenny
add in a nice cleaner shrimp, some snails, and a couple of hermits and you have an interesting tank, just remember you will have to be very good with maintanance, which I am sure you will be
Seffie x