This relates to another message in the Baths forum, but basically I am looking for advice on how to properly insulate along the exterior wall(s) of a bathroom. A recent energy audit showed that there is no insulation along the exterior wall adjacent to where the tub sits.

Should I attempt to temporarily remove the tub and install some form of rigid insulation along the exterior walls, or would a foam application work best?

The same energy audit also showed that there is little -- if any -- insulation in the boxes under the addition that house the duct work. Should I install rigid insulation around the boxes? Remove the boxes? Inject foam? Caulk around joints?