Short answers, pulled from the story.
The Council for Mutual Economic Assistance emerged from a Moscow conference held between the 5th and the 8th of January 1949. Six nations gathered to sign its founding charter: the Soviet Union, Bulgaria, Czechoslovakia, Hungary, Poland, and Romania.
Stalin shifted the organization's direction dramatically during the summer of 1950 as the Soviet Union moved toward autarky domestically. International relations became an embassy system of direct meddling rather than constitutional means while Nikolai Voznesensky lost his patron after August 1948.
Comecon operated on unanimous agreements until 1967 when it adopted the interested party principle. Any country could opt out of projects they chose while others continued using mechanisms to coordinate activities.
The Soviet Union possessed 90 percent of land and energy resources among all Comecon members. It held 70 percent of population and 65 percent of national income across the bloc with industrial and military capacities ranking second globally only behind the United States.
The final council session took place on the 28th of June 1991, in Budapest agreeing to dissolve within 90 days. The Soviet Union itself dissolved on the 26th of December 1991.