The cape was actually, like I expected, the hardest thing to rig. And it's still not perfect, but it's the best results I got out of every attempt. Kinda sucks, it would be perfect if the game would allow a new skeleton with multiple animations in it, but or better said, if the Alchemy exporter would allow it, but it doesn't. Otherwise I could've animated the cape if anything.
I haven't tested these skins with the Emma Frost mod. Don't have it installed anymore, I just mod for fun.