Depends on the 2 clowns you want to get, but most of the fishes you listed are pretty small and you can add probably 2-3 more fishes (depending on size).
I would add these:
and maybe a tang (so that the neon goby has someone to clean!)
But remember, take it slow! You should definiately have enough room for 3 of the 4 fishes I listed above. The tang is iffy, I'm sure it can be done if you pick up the smaller tangs like the Yellow Tang or the Yellow Eye Kole Tang. They typically grow 5-6 inches in captivity.
Oh yea....are you sure you want that damsel in there? Not that damsels are bad looking but you might regret that fish when it comes down to adding other fishes, they can be pretty mean and I would never add one again even if you paid me.