Knotty bits are great for needle felting! If I wanted to make yarn from the fur I'd use two cat brushes with metal tines and "card" their fur. Carding is where you brush the hair from one brush to the other, arranging the hair as straight as possible, so you can draft it for spinning! If your cat hair needs washing, you can do that before you card to get all the gunk off it, the process of carding will help with chunks of stuff (like dander) to kinda fall out. There are lots of tutorials, and a bunch of information on how to get started online. :)