What is a train line on a single rail called?

What word for a singable poem appears in the title of Sir Walter Scott's "The ___ of the Last Minstrel"? Which singer had a hit with "Stand by Your Man"? What is a single edition of a magazine called? A single mom leads a legal fight against Pacific Gas and Electric in which 2000 drama? What is a single residential building divided into three units called? What is a single-seat aircraft powered by a small motor called? What is a single show of a TV drama series called? What is a single unit of hereditary information called?