Cherry barbs aren't very nippy. I have 3 in with my Opaline gourami in my 29g and they don't bother him. They also aren't really schoolers. They do enjoy the company of their own kind, but a pair or trio is ok. Ottos are the same. I wouldn't call them schoolers, but shoalers. They like a little group, not necessarily a school (which would mean 6+).
I would up the danio school, to atleast 6. If they are the only schooling fish you want, you could even have 8.
Dwarf gourami males don't get along very well, so if you want one, just get one. Usually males are all you can find in LFS. Another option is a honey gourami. I think they are more peaceful than the dwarves, but stay the same size. I'm not sure about keeping more than one of them though. Usually gouramis should either be kept in large groups, or alone. Dwarf gouramis are the worst about not getting along though, IMO. They are fine by themselves.