in a 14 gallon I'd stick with 2 or 3 of each kind, ceriths, nass, astera (sp) and maybe, maybe 1 turbo if you start to get algae growing like crazy.
Maybe 1 or 2 hermits? They may eat your snails.
No the clown doesn't go to the back because the chromis kicks it out. The chromis just hides in the back and once the clown tried to go to the back it gets chased off.