For the tails, you could use the yarn method that people use to make tails for their fursuits. Tutorial
The keychain looks like what you might want for the shoulder tails.
As for the wig, I've seen one Joker cosplayer take a bald cap, and add wig hair to it. I bet if you look up how to do that on google or something, you could find a tutorial on how to do that.
Hope that helps. (: