mask/slice actions in the NLA editor, and some way to freeze child bones (such as feet during transitions)

It would be really handy if instead of having to duplicate actions to edit them, you could just slice and dice them directly in the nla editor non destructively. Like in adobe premiere for example.

Also, i'm finding if I have a walk cycle strip leading to a standing strip, the feet slide around as it transitions. It would be handy if there was a freeze/pin bone listbox for all children of the action. Then you could just freeze each foot independantly at it's last footfall so they stay stationary?