So, here's what I know about desynthing so far. ilvl ?-49 gear can desynth into Demimateria Is. The higher end of that yield two of them when they give you Demimateria. ilvl 55 items can yield Demimateria II (and never give Is), and often give two (though I've also gotten one once). I'm scared of what ilvl is required for a chance ato the Demimateria IIIs or the Matercraft Demimateria. When they give (non-clear) Demimateria, DoW/DoM items can yield Battlecraft Demimateria, and DoL/DoH items can yield Fieldcraft Demimateria.
You can get the new books and the new tools from the same guy who sold the old books and the old tools. To get the new books, each one costs 5 Fieldcraft Demimateria I and 5 Battlecraft Demimateria I (really not that bad, I already have two of the books). To get the new tools is a different story... The tools require 5x of the new token items. Each token item costs 2x Fieldcraft Demimateria III to craft. I don't even know what you have to desynth to get Fieldcraft IIIs, but I'm scared it'll wind up being the old Artisan tools. I don't know of anything else above ilvl 55 for crafters or gatherers, and ilvl 55 has only given me IIs so far.
There are additional requirements for the new tools, but I can't recall them off the top of my head. I think they also require Mastercraft Demimateria, but I don't remember how many. The new tools aren't that much better than the Artisan ones.
(FYI, unlike when converting, the Aetheryte Ring yields Fieldcraft Demimateria - very nice for GSMs given how cheap they are to make)