Seriously, is it possible to actually find werewolves out & about in Skyrim? I have heard you can, but I've also heard that there's a mod that brings them in as enemies at night. So I figured it's just a mod, since I've gone 300+ hours with never seeing one.

You can find them randomly out in the wilderness if you have DG installed.

With vanilla skyrim, no, though I think they were intended to be encountered in the wild.