Way out of my league as well, but managing physics objects should be relatively simple as Bullet is already integrated and I guess it works internally with Panda3D bones and primitives (as collision shapes) that you just need to display and let people play with the bullet settings. For example the maximum rotation of a joint or the mass of an object etc.
Procedural animations are of course a complicated topic, but I am guessing that most of the work is already done in the smartbody stuff that has been integrated with Panda3D, see:
smartbody.ict.usc.edu/
Maybe exposing a simplified version of that in your editor and allowing people to ‘bake’ those animations as keyframes so that you don’t have to run the full simulation in your game would be a good start?
Edit: Smartbody also recently added a automatic reshaping and rigging tool, which would be really awesome to have in an editor for humanoid characters. See: smartbody.ict.usc.edu/news/autor … l-released