Thanks!
Well, Iceborn showed the way and the how. Yeah, one can use Blizzard models, animations, and other resources freely in WC3 now, as long as it's for entertainment purposes and not any profit from this, of course.
Similarly, with DOTA 2 or Valve models, which Iceborn also used, there is a way to use these resources as well, by including the disclaimer like Iceborn team did and which I'm using for my Centaur Horde Campaign as well.
Regarding uploading these units/buildings separately, as not part of the campaign, I think the same disclaimers can be used, as long as it's credited when uploaded. However, I wasn't planning on uploading separate, individual units/buildings. Yet, by crediting the same disclaimers and letting users know from whence these models/animations came about and my only contribution is importing/customizing them to fit into WC3, then I could upload these units/buildings/heroes separately, only if people really want.
There are DOTA mods for WC3 that convert everything into DOTA 2 models/animations/textures, so I don't see this as a problem. I do recognize that Hive Workshop did ban this importing before, but now it's a non-issue, based on this thread here:
http://www.hiveworkshop.com/forums/faq/realfaq/
and here:
http://www.hiveworkshop.com/forums/latest-updates-news-101/game-exports-foo-fighters-blizzcon-2011-new-starcraft-novel-204461/
Do correct me if I'm wrong though. Still, I'm just inspired by what Iceborn did was able to accomplish and allowed to accomplish. That's all :D