Next time I will find the foot problem I will post pics of what it looks like. But from what I remember, my foot roll animation was correct at some point, then I did something, maybe rotate the COG, and then the foot was sliding like crazy.
Timewarps is a function of CS`s Mixer and from the doc and some tests, I didn`t see any way to invert an animation.
I also noticed a limitation in the FK/IK switch of this rig: with keyframing tools > separate tracks > `arms` checked, it just does not work: if you rotate the arm, then move the hand, then set a key, the arm will go back to its rotations before moving the hand.