Lots of great info given here, I would add this;
Since the 60's, I have and still use heads of various designs and manufacture on my single hand rods. They range in length from 27' to 35', floating, intermediate, fast sinking, to a Sunset line that is 32 grains to the foot. The designs are off the shelf, hybrid types(with and without looped tips), to custom compound formulations. The method of forming loops for attachment to tips or running line are explained above. As for running lines I have mono lines 30# Amnesia, 50# Slick Shooter, 80# Frogs Hair for various situations. My favorite running/shooting line is Airflo ridge in 20# or 30#, easy to handle and never lose my grip, which can be problematic with mono when it gets wet. Lastly, yes for use as a tool to get more distance in the casts.
wcglass