Short answers, pulled from the story.
Gleb Krzhizhanovsky, Friedrich Lengnik, and Vladimir Noskov took their seats to supervise the party newspaper Iskra. This small group held the right to decide all party issues except local ones.
Of the 139 people elected to the committee, ninety-eight were killed or imprisoned during this period. By the 18th Congress in 1939 only thirty-one members remained and just two had been reelected from the previous body.
Georgy Malenkov succeeded Stalin as chairman on the 5th of March 1953 but resigned from the Secretariat by March 14 to grant the request of the Council of Ministers chairman. Lavrentiy Beria contested power alongside Malenkov and Nikita Khrushchev forming a short-lived Troika until they betrayed him.
Mikhail Gorbachev was elected General Secretary unanimously on the 11th of March 1985 following Chernenko's death four days earlier. The Politburo recommended Gorbachev to the Central Committee which approved him without opposition from Dinmukhamed Konayev Volodymyr Shcherbytsky or Vitaly Vorotnikov.
The committee officially disbanded upon banning the CPSU in late 1991 after years of accelerating disintegration of party control. In 1990 the Congress of People Deputies voted to remove Article 6 from the 1977 Soviet Constitution ending the Communist Party's position as leading force.