Short answers, pulled from the story.
The Strategic Arms Limitation Talks began in Helsinki on the 17th of November 1969. Gerard C. Smith led the American delegation as director of the Arms Control and Disarmament Agency.
SALT I froze the number of strategic ballistic missile launchers at existing levels. It allowed new submarine-launched ballistic missile launchers only after dismantling older intercontinental ballistic missile launchers.
Carter withdrew the treaty from consideration in January 1980 because six months after the signing the Soviets invaded Afghanistan. The United States also discovered that a Soviet combat brigade was stationed in Cuba since the Cuban Missile Crisis of 1962.
The total number of missiles held by the United States remained static since 1967 at 1,054 ICBMs and 656 SLBMs. An increasing number of missiles with multiple independently targetable reentry vehicle warheads were being deployed during this time.
A successor to START I New START was proposed and eventually ratified in February 2011. SALT II sought to curtail the manufacture of strategic nuclear weapons from 1972 to 1979.