My wife's obsessed with dwarf puffers, so I've started researching getting her a tank. I have not heard of bumblee gobies as being good specifically with dwarf puffers - they are brackish and thus prefer the same water quality as most puffers...
The nice thing about dwarf puffers, in addition to their small size and thus small tank requirements, is that they can live fine in freshwater as opposed to most other puffers. In general, they are best in a species tank. I have heard of people keeping oto cats with them - in a heavily planted tank they may be able to avoid the puffers and keep your tank clean. The brackish fish that are suggested can go with puffers, like monos and scats, are big and will probably eat a dwarf. MTS snails might survive with the dwarfs. I'd be interested in hearing what shrimp species is best - I like the idea of cherry reds so easily breeding and was going to get some for my community tank.
For stocking density, I'd probably go conservative on the 1"/gal rule and for example have max 5 puffers in a 10 gal. The more plants/driftwood/rock structures, the better.