A: It would help but not sure how much without more information. There are other products that you may also want to consider. There is a foil faced foam board that is available in different thicknesses. This may provide a level of insulation between the outer wall and the pipes.
A: Yes it can and should help. It is important to NOT let the electric mat and the reflective foil to come into direct contact.
A: Steve, The roll is 125 feet long.
A: Patrick, I believe that the Uponor quick track has an aluminum heat plate attached to the quick track. If that is in fact the case I don't believe that you would need to ad thermal reflecting foil. You may want to do additional research as I am not that familiar with Uponor products.