I think you have to tap the axis key to cycle to your selected transform orientation. So for example: Set transform orientation to "normal", G to move, Z to constrain to Global Z axis, Z again to constrain to Normal Z axis, Z again to cycle back to unconstrained move.
You can't use Biped to animate heads/arms falling off. You've got a couple of options. 1. Use a custom rig instead of Biped. 2. Skin your objects to Helpers that are constrained to the Biped. Then at the frame the limb needs to be cut of animate the constrain to a controller object that doesn't follow the biped.
I have to say, thanks Eric! I tested everything today and it works perfectly. What I did was, just what I said basically. Attach constrained a bunch of dummy boxes to key areas of the morphing mesh (as per the XSI facerobot example bone structure), then Position Constrained a bone to each dummy object. For the eyelids,…