Short answers, pulled from the story.
In Western Europe, the Eastern Bloc primarily comprised the USSR and the Warsaw Pact nations: East Germany, Poland, Czechoslovakia, Hungary, Romania, Bulgaria, and Albania. In Asia it included Mongolia, Vietnam, Laos, Kampuchea, North Korea, and South Yemen. In the Americas, Cuba aligned with the Bloc from 1961, along with Nicaragua and Grenada for shorter periods.
The Eastern Bloc existed from 1947 to 1991, spanning the duration of the Cold War. Its foundation rested on Soviet expansions that began in 1939-1940 with the Molotov-Ribbentrop Pact and the annexation of the Baltic states, and it dissolved with the end of the Soviet Union in 1991.
Between 1950 and 1961, approximately 3.5 million East Germans fled west through a loophole created by the Berlin city sector borders, which all four occupying powers administered and which were considerably more accessible than the closed Inner German border. The flow reached 331,000 in 1953 alone, representing roughly 20 percent of the entire East German population before the Berlin Wall was erected in August 1961.
Interkosmos was a Soviet-led space cooperation program founded in April 1967 to coordinate spaceflight among Soviet-aligned socialist nations. Its first crewed mission, Soyuz-28, lifted off from Baikonur Cosmodrome on the 2nd of March 1978, carrying Soviet cosmonaut Aleksei Gubarev and Czech cosmonaut Vladimir Remek to the Salyut 6 Space Station. It was the first crewed spaceflight to include a crew member from neither the United States nor the Soviet Union.
Eastern Bloc economies were centrally planned, with investment directed overwhelmingly toward heavy industry at the expense of consumer goods. By the mid-1970s, production prices averaged two percent above consumer prices, budget deficits rose considerably, and most countries were borrowing from creditor clubs and facing insolvency by the early 1980s. Black markets filled gaps left by chronic shortages of basic goods including food, clothing, and household items.
The Tito-Stalin split occurred after disagreements between Yugoslav leader Josip Broz Tito and the Soviet Union over Greece and Albania, resulting in Yugoslavia's expulsion from the Cominform in June 1948. Stalin responded by converting the Cominform into a surveillance tool, instructing Soviet cadres to foster conflict within Eastern Bloc party leaderships. In Poland, Wladyslaw Gomulka was jailed; in Bulgaria, Traicho Kostov was arrested and executed; in Hungary, Laszlo Rajk was tried in a show trial and executed.