The spinning is a circular dependency issue. I think you might have your VR rig parented to the avatar. If so, VRIK will turn the root when you turn the head, that in turn rotates the VR rig and in the next frame the same thing happens all over again, causing it to spin.
About the tip toeing, please try adjusting some variables in the Spine settings, like reducing "Neck Stiffness" and/or "Body Rot Stiffness".
Also, moving the head target backwards relative to the avatar might help too.