I have crit that is going to be painful after all that detail. You are using a ball joint at the knee. A ball joint will limit the movement when you go to animate it. Do a test and rotate the leg and you will see you will only get a few degrees of movement. I would use a hinge joint there. ball joints are good for hips where it does a swivel motion on the joint. In otherwords, now rotate that joint in a twist motion like you are trying to twist the leg off under the knee. It can rotate like that 360 degrees. If the bll joint came out of the knee sideways it would work.