As for moving the main joint...I have a bit of a delemma with that...
Lets say you have the main joint move downwards for a crouch animation.
Now...each frame the joint thinks 'ah i need to move downwards a few pixels' and it all works sweet.
But now you bang in a platform behavior object, and add the action:
Always - Set position of body to player
This means each frame the body is positioned to the player, and then it moves down a few pixels...resulting in no movement at all....
So I'm still unsure of how to resolve this one...