Q: 1. Is there any way to limit what joints are rotated when I move a body part around? For example, when dragging the left hand, I'd like only the hand, lower arm, upper arm, and shoulder to adjust. Not any of the trunk nodes.

A: Yes there is. Its the little used or discussed "Chain Break". When you use the Translate/Pull tool, poser uses a kind of temporary IK to affect a number or actors by the dragging. Applying  Chain Break to an actor will will break this IK chain for the actor it is applied to, and stop the IK effect propagating to, or past,  this actor. It's different from locking an actor. If I lock the collar, the IK effect of dragging the forearm will still propagate through the collar and chest, and end up bending the abdomen. If I use Chain Break the effect won't propagate through the collar.

The Chain Break Tool, is in the Editing Tools pallet. Read the Poser manual for more details.