Short answers, pulled from the story.
The Union of Soviet Socialist Republics was formed in December 1922 when the Russian SFSR merged with other republics. Joseph Stalin initially resisted Lenin's proposal for a unified union but eventually accepted it.
Forced collectivization of agriculture began shortly after 1928 and caused a famine that killed millions between 1930 and 1933. Resources were mobilized for rapid industrialization to transform the USSR from an agrarian economy into a great industrial power.
The Soviets suffered an estimated 27 million casualties, which accounted for most losses among the victorious Allies. Millions died in the conflict including excess deaths throughout World War I and the Russian Civil War that amounted to 18 million combined.
The USSR launched Vostok 1 carrying Yuri Gagarin as the first human to ever be launched into space on the 12th of April 1961. Valentina Tereshkova became the first woman in space during a later mission.
Gorbachev officially recognized the dissolution of the Soviet Union on the 26th of December 1991. Boris Yeltsin oversaw the reconstitution into the Russian Federation on the same day.