Yes, I have seen pictures of the old Ever-Ready brushes and I would love to find one so that I could try it out. I think that they may have been boar. Speaking of which, take a look at the link in my first post. There are some pictures comparing the different types on brushes and it may help you to identify the types of brushes that you currently have.

I don't know much about the knots, other than the fact that they are measured in millimeters and there are several different sizes. Maybe someone will chime in later and explain it all to us.