Short answers, pulled from the story.
The U.S. Army began studies for a ballistic missile with a range of about 300 miles in 1956 following a meeting between George Bunker and General John Medaris at Redstone Arsenal in Alabama during that same year.
The Martin Company received a cost-plus-fixed-fee contract for research and production after a selection process led by General Medaris and Dr. Arthur Rudolph.
The Y1 option provided 60 kiloton yield while the Y2 offered 200 kilotons and the Y3 delivered 400 kilotons.
A total of 754 MGM-31A missiles had been built before complete phase-out commenced.
Final destruction occurred in May 1991 after withdrawal procedures began in October 1988 following ratification of the Intermediate-Range Nuclear Forces Treaty on the 27th of May 1988.