Short answers, pulled from the story.
The KGB officially dissolved on the 3rd of December 1991 after decades of operation spanning from 1954 to 1991. This dissolution followed a failed coup attempt in August 1991 that marked the beginning of the end for the organization.
Ivan Serov became the first chairman of the Committee for State Security following its emergence on the 3rd of March 1954. He took office after a restructuring that followed the fall of Lavrenty Beria in June 1953.
The KGB carried out internal security, foreign intelligence, and secret police duties across the Soviet Union throughout its existence. The agency operated as a military service governed by army laws and attached itself directly to the Council of Ministers.
KGB operatives infiltrated spies into Solidarity and the Catholic Church through Operation X despite Polish United Workers Party hindering destruction efforts. They coordinated martial law declaration with General Wojciech Jaruzelski but vacillating Polish approaches blunted overall effectiveness.