Short answers, pulled from the story.
The Central Committee of the Communist Party of the Soviet Union was the highest governing organ of the CPSU between party congresses. Elected by the Congress, it held de facto supremacy over the Soviet government, though real authority was often exercised by smaller bodies it elected, namely the Politburo, Secretariat, and Orgburo.
The Central Committee originated in the Russian Social Democratic Labour Party, founded in 1898, and continued in the Bolshevik party established in 1912. It was officially disbanded when the CPSU was banned in late 1991.
Stalin used control over personnel appointments to dominate the Central Committee and ensure ideological conformity. During the Great Purge of 1936 to 1938-98 of the 139 members elected at the 17th Party Congress were killed, reducing the committee by 78 percent. By the 18th Congress only 31 members remained, and only two of those had been reelected.
On the 14th of October 1964, the Central Committee voted alongside the Presidium to remove Nikita Khrushchev from all his posts, replacing him with Leonid Brezhnev as First Secretary and Alexei Kosygin as chairman of the Council of Ministers. The committee cited nepotism, unauthorized policy decisions, and a cult of personality as grounds for his removal.
Under Leonid Brezhnev the Central Committee expanded significantly, growing to 195 full and candidate members after the 23rd Congress in 1966, 287 after the 25th Congress in 1976, and 319 after the 26th Congress in 1981. The survival ratio of members between congresses peaked at 89 percent at the 26th Congress.
Mikhail Gorbachev used the Central Committee to pursue glasnost, transforming it into a more open deliberative body. On the 30th of September 1988, a Central Committee resolution established six new Commissions covering international affairs, agriculture, party building, ideology, socio-economic questions, and legal affairs. He also used the 19th Party Conference in 1988, the first since 1941, to debate term limits, multi-candidate elections, and reducing nomenklatura privileges.