Sort of a dated thread, but since I have some information that might be useful for others who do a search....
1) There is no working chamber on Noronha. There is a building, I guess, but no funds to actually install a chamber and operators. Also it's a really long way from the coast, so the only way in and out for a seriously sick patient is by air, and the airlines go too high for safe transport of a bent diver. You just have to make sure not to get bent!
2) In terms of the challenges presented by diving at Noronha, there is something for everybody. The morning dives are generally more challenging and are offered in the Mar de Fora area where sea conditions are rougher. The afternoon (and training) dives are generally at the Mar de dentro, where the water is quieter and shallower.
3) There are three operators on the island. I like both Atlantis and Aguas Claras. I think AC is friendlier, but Atlantis has tech diving. Noronha Divers is the budget option.
4) There are tons of pousadas to stay at. Nothing at Noronha is cheap, though, so you pay a lot for very modest accommodations. Solar dos Ventos is one of the more upscale places. Cheaper places are available in the village.
I've been to Noronha many times, and have some photos up on Virtual Tourist under the same screen name I use here.