1. See sixfins answer. Also add FloridaCollector.com
2. Total? You could easily house two dozen dwarfs in a 5 gal tank. However, DO NOT start with that number. As was advised, 3 or 4 pair to start would be adequate.
3. The best food would be a varied diet of copepods and other larval foods small enough for the dwarfs to eat. The majority of us keeping them feed a mix of newly hatched brine shrimp, enriched brine shrimp and copepods. The food must be live. The easiest food to use is newly hatched brine shrimp, but it's not nutritionally complete.
4. Either fake plants/decor or live plants pre-treated with panacur to eliminate any hydroid issues.
5. No fish. Period. Tankmates could include nassarius snails, which will survive a panacur treatment. Anything live added to the tank, whether it be rock, plants, snails, etc must be pre-treated to eliminate hydroids. Only some species can withstand that treatment.
6. It's not needed, but makes things easier and nicer to look at IMO. Without a substrate you'd need a superb biological filter somewhere to keep ammonia levels at 0. Water parameters go out of whack pretty quickly with only 5 gal of water and heavy feedings.
7. No special lighting. I use a standard normal flourescent bulb.
8. As soon as the tank is fully/completely cycled I would add the clean up crew. If parameters stay acceptable, you're good to go for adding the dwarfs.
9. Tank conditions for dwarfs really don't suit many corals very well. Gorgonians are ok, but require more current than can be offered in small 5 gal tank. Without current algae tends to grow on the gorgonians and they fail to open/capture food and perish over time.
10. As you think of more questions.... just ask away
Tom