Short answers, pulled from the story.
Willy Brandt was born Herbert Ernst Karl Frahm. He adopted the pseudonym Willy Brandt in 1933 when he fled Germany for Norway to escape Nazi persecution, using the false name to avoid detection by Nazi agents. He formally adopted it as his legal name in 1948 when he rejoined the SPD and regained German citizenship.
The Kniefall von Warschau was an unplanned, spontaneous gesture by Willy Brandt in December 1970, during a visit to a monument commemorating the Warsaw Ghetto Uprising. Brandt knelt silently before the memorial, honoring the victims of the German occupation. The moment drew strong positive reaction worldwide but was highly controversial among the German public at the time.
Willy Brandt received the Nobel Peace Prize in 1971 for his efforts to strengthen cooperation in Western Europe through the EEC and to achieve reconciliation between West Germany and the countries of Eastern Europe. His Ostpolitik included the Treaty of Moscow in August 1970, the Treaty of Warsaw in December 1970, and the Basic Treaty with East Germany signed on the 21st of December 1972.
Brandt resigned on the 6th of May 1974 after his close personal aide Gunter Guillaume was arrested on the 24th of April 1974 and revealed to be a Stasi agent. The Guillaume affair is widely considered the trigger rather than the fundamental cause; Brandt himself later said he was exhausted for reasons unrelated to the espionage scandal. Markus Wolf, head of the East German foreign intelligence service, later said that Brandt's resignation had never been the intended outcome of the Guillaume operation.
Brandt's government nearly doubled public spending on social programs between 1969 and 1975, raised the university student population from 100,000 to 650,000, and grew the education budget from 16 billion to 50 billion Deutsche Mark. The 1972 Pension Reform Law guaranteed a minimum pension for all retirees. The voting age was lowered from 21 to 18, corporal punishment was banned in schools in 1971, and compulsory health insurance was extended to the self-employed.
Ostpolitik was Brandt's policy of engaging diplomatically with Eastern Europe rather than isolating it. It included treaties with the Soviet Union and Poland that formally accepted post-World War II boundaries, including the Oder-Neisse line. It was deeply controversial in West Germany because many displaced Germans and their descendants, who had been driven west from Historical Eastern Germany and the Sudetenland, called it illegal and accused Brandt of high treason. Supporters argued it helped break down the Eastern Bloc's siege mentality.