Is it psoble to make something like UA mod for SS, maybe adimg new units or factions lile IG or Chaos
Not possible, and from what was said so far it will never be possible.
Not yet. Whether or not the ability to mod DoW 3 to the extent that DoW 1 was moddable has yet to really be seen, but the official mod tools have a lot of broken and/or missing stuff right now. Once they're up to speed, it might be more plausible to do that.