I'm pretty sure the Greys in MRG are just thrown out as a random plot hook, like lots of other elements in the guide (Hyperelites collecting Flats, anyone?), and thus is not a fleshed out element, and unlikely to be fleshed out. It is up to the gamemaster to use based on the information. I would assume they are a small clade focused on jokey sci-fi tropes, similar to some of the Scum Swarms which play out like giant LARPs. Otherwise they may live standard redneck lives. As for the Sufis, I believe the extent of the canonical information lies in the opening of Sunward, discussing where they came from and their general attitude. Might be a snippet in Transhuman discussing "Sufi Nomad" as a background. Caravan types is kind of covered in the gear section though, since it introduces the Martian Rover, a vehicle typically used by Martian Nomads. Combine with some other mars adapted vehicles, and you're set. Vehicles aren't really specified down to make and model in EP, so you'll have to deal with generalizations. For Morphs, more Sufis are probably in their original Flats or Splicers, possibly adapted for Martian conditions, with maybe some Alpiners or Rusters, but unlikely due to Hypercorp interference. I don't really understand the request for "elder details, backgrounds, etc", but if you want to know more about the Sufis, you might want to look into actual Sufism, which is the philosophy the nomads are based on.