Short answers, pulled from the story.
Otto von Habsburg was born at Villa Wartholz in Reichenau an der Rax, Austria-Hungary on the 20th of November 1912. His full baptismal name included Franz Joseph Otto Robert Maria Anton Karl Max Heinrich Sixtus Xaver Felix Renatus Ludwig Gaetan Pius Ignatius.
Otto von Habsburg renounced all claims to the Austrian throne on the 31st of May 1961 for purely practical reasons to regain citizenship. The Austrian administrative court found this statement legally sufficient on the 24th of May 1963 allowing him to return home.
Otto von Habsburg co-organized the Pan-European Picnic at the Hungary-Austria border on the 19th of August 1989 which accelerated the fall of communist regimes. This event served as a symbolic opening of the Iron Curtain for thousands of East Germans seeking freedom and is considered a milestone in European history.
Adolf Hitler personally revoked the citizenship of Otto von Habsburg, his mother and his siblings in 1941 leaving them stateless. He helped around 15,000 Austrians including thousands of Jews flee the country while serving as an unofficial head of resistance groups in Central Europe.
Otto von Habsburg visited his home country again on the 31st of October 1966 for the first time in 48 years after receiving an Austrian passport on the 1st of June 1966. His body was laid in repose in the Church of St. Ulrich near his home in Bavaria on the 5th of July 2011 following his death.