Short answers, pulled from the story.
Joseph Stalin was the first General Secretary of the Communist Party of the Soviet Union, elected to the role at the 11th Party Congress on the 3rd of April 1922. He was appointed by Lenin, though Trotsky later attributed the recommendation to Grigory Zinoviev. Stalin served as the longest-tenured General Secretary at thirty years and seven months.
Vladimir Lenin created the office of General Secretary in 1922 after the Bolshevik victory in the Russian Civil War. His intention was that it serve a purely administrative and disciplinary purpose, primarily determining party membership composition and assigning positions within the party.
In his final months before his death in 1924, Lenin authored a pamphlet calling for Stalin's removal on the grounds that Stalin was becoming authoritarian and abusing his power. A vote was held to remove Stalin from office, but he survived it with the help of Grigory Zinoviev and Lev Kamenev.
The office of General Secretary was not renamed to First Secretary. The reverse occurred: after Stalin's death, Nikita Khrushchev was elected to the new office of First Secretary in September 1953. The office was then renamed back to General Secretary at the 23rd Party Congress in 1966, under Leonid Brezhnev.
Mikhail Gorbachev resigned as General Secretary on the 24th of August 1991 in the aftermath of the failed August coup. His deputy, Vladimir Ivashko, served as Acting General Secretary for five days before the party's activities were suspended on the 29th of August 1991.
The Communist Party of the Soviet Union was formally banned on the 6th of November 1991 following the suspension of its activities in August that year. In 1993, Oleg Shenin established the Union of Communist Parties - Communist Party of the Soviet Union, an organisation dedicated to reviving and restoring the CPSU, with members across all former Soviet republics.