11. Is it true that Beethoven, who moved to Vienna in November 1792 and died in March 1827, lived in more than 70 appartments over the years?

Yes and no. It's a fact that Beethoven, always discontent and restless, very often moved, sometimes within a few weeks or months. But without more information one should get the wrong impression. In his days most well-to-doViennese used to leave the dirty, stinking city during the warm summer months and moved to a pleasant residence abroad, mostly somewhere in the beautiful Wienerwald. They often left in April or May and returned by the end of October. Sometimes they hired a new appartment on returning to the city, sometimes they returned to their old winter residences. Beethoven followed their tracks in this respect. Being so restless he mostly moved into a new appartment in October and more than once he was not satisfied with the summer appartment(s) he had chosen and then decided to move from one residence to another.

See:
Klein, Rudolf. Beethoven Statten in Osterreich. (Vienna, 1970).
Smolle, Kurt. Wohnstatten Ludwig van Beethovens von 1792 bis zu seinem Tod. (Bonn, 1970).
Cooper, Barry. The Beethoven Compendium. (London, 1991).
Kretschmer, Helmut. Beethovens Spuren in Wien. (Wien, 1998).
Brauneis, Walther. Beethoven-Hauser. (Bonn, 2001).