Ok, i'm working on the basement to get it ready for a famly room and all that. anyway..

Is it worth it to insulate the duct work? I was having a hard time seeing it being worth it.

and my second question is. Should i tap into my return so it pulls from the basement as well? thanks.

Insulating on the outside probably isn't worth it. The areas that your ducts will be going through will be interior spaces. Some people put duct liner inside the duct work to reduce noise.

You will need to put in returns in order to properly ventilate the area, air won't move (well) without a supply and a return.

Greg

ok, so would the best way be just to tap into my current return? that was my plan

Check the capacity (data label) of your furnace and air conditioning to see if it can handle the increased sq footage of the room(s) you're adding. My brother in law does hvac and did a load analysis for me on our 1000+ sq ft basement and the existing hvac could handle the increased load by tapping into the existing ductwork for heat and air conditioning and also putting in returns. Your situation might be different, but it's worth having someone come out to check it out.