Short answers, pulled from the story.
East Berlin became the capital of East Germany when the German Democratic Republic formed in 1949. All communist countries recognized this claim while Western Allies never formally acknowledged the authority of the East German government over East Berlin.
During the blockade of June 1948 all railways and roads leading to West Berlin were blocked so that East Berliners could not emigrate. More than 1,000 East Germans escaped to West Berlin each day by 1960 due to strains on the economy from war reparations owed to the Soviet Union.
The population reached its highest point in 1988 with 1.28 million residents. The lowest value occurred in 1961 when under 1.06 million were registered before reunification.
Eberhard Diepgen became the first elected mayor of a reunited Berlin taking office in January 1991 following citywide elections in December 1990. On the 3rd of October 1990 East and West Germany and East and West Berlin were reunited.
The Berlin Wall remained up until the 9th of November 1989 after the East German Government tried to stop the population exodus in August 1961. Armed soldiers were trained to shoot illegal emigrants crossing the border making crossing very dangerous for fleeing residents.