I hope gunpowder does get added in even if only as a minimod. I can see good applications for it, and not just for dwarf factions or Ironeers - my sci-fi faction could do well with flintlocks, since they'd know more about gunpowder than some other faction who would be researching it, it'd be just a matter of rediscovering it. Same thing in the Warfare tree though, I'd imagine. However...
The XML is no problem, however there are no unit animations or models. That will require a significant effort on your behalf to learn.
Still, I hope that someday gunpowder weapons in Elemental will be a reality. Good luck with that extra stuff with modelling and that (or finding someone willing to help), Apoc, I'd be hopeless at that personally, sorry 