Short answers, pulled from the story.
The Czechoslovak Socialist Republic's Communist government took power on the 25th of February 1948, when President Edvard Benes capitulated and appointed a Communist-dominated cabinet. The Ninth-of-May Constitution formally declared the country a people's democratic state on the 9th of June 1948. The name Czechoslovak Socialist Republic was officially adopted on the 11th of July 1960 under the 1960 Constitution.
Rudolf Slansky and eleven others were convicted of being Trotskyist-Zionist-Titoist-bourgeois-nationalist traitors and were executed. Their ashes were mixed with material used to fill roads on the outskirts of Prague. Vladimir Clementis was also executed in the same wave of purges.
The Prague Spring was a period of liberalizing reforms under First Secretary Alexander Dubcek, who took office on the 5th of January 1968. It ended on the 20th-the 21st of August 1968 when the Soviet Union and Warsaw Pact jointly invaded Czechoslovakia. Dubcek was replaced by Gustav Husak on the 17th of April 1969, who reversed the reforms in a period known as normalization.
Following the 1948 Tito-Stalin split, 550,000 members were expelled from the Communist Party of Czechoslovakia, representing 30 percent of its total membership. Many of those purged had prior memberships in other political parties before joining the Communists, which was treated as grounds for suspicion.
The Velvet Revolution of late 1989 forced the Communist leadership to resign. On the 30th of November 1989, the Federal Assembly removed the constitutional provisions giving the Communist Party a monopoly on power. Democratic elections in June 1990 brought the Civic Forum to victory, and the state was renamed the Czech and Slovak Federative Republic in April 1990. On the 1st of January 1993, the country split into the Czech Republic and Slovakia.
Religion was systematically repressed. In 1950, the government executed Operations K and R to dismantle monastic life and confiscate ecclesiastical property. More than 6,000 religious people received prison sentences averaging more than five years each, and between 1948 and 1968 the number of priests declined by half.