I'm using Buiodda's mod, so I don't make cords from hide any longer, so I don't remember if you get any quality out of that process (and I didn't care anyway, as any cord is good for preserving meat).
Skunks are native to North America, not Europe, as far as I know, and according to Wiki skunks are different from polecats, although "In the United States, the term polecat is sometimes applied to the black-footed ferret, a native member of the Mustelinae, and (loosely) to skunks, which are only distantly related".
I'd expect those small predators to take advantage of snared birds, yes.
My experience with wounded hunter quests is that those predators are more aggressive than normal (I've lost one character on such a quest, and have had characters attacked at least once, and probably twice on them). I'm now taking extra care in those quests...