Short answers, pulled from the story.
Bonn holds the official title Bundesstadt, or Federal City, because it retains a significant presence of German federal government functions after the capital moved to Berlin. As of 2019, approximately one-third of all ministerial jobs remain in Bonn, and the city holds the primary seats of six federal ministries and twenty federal authorities.
Bonn served as the capital of West Germany from 1949 to 1990 and then remained the seat of government for reunified Germany until 1999, when parliament and most government functions relocated to Berlin. The period of Bonn's role as capital is known among historians as the Bonn Republic.
Yes, Ludwig van Beethoven was born in Bonn in 1770, in a house on Bonngasse near the market square. He was baptized at the church of St. Remigius in Bonn, and his birthplace is now the Beethoven House museum.
Bonn is among Germany's oldest cities, with evidence of human settlement dating back around 14,000 years to a double burial found at Oberkassel. Roman forces built a legionary fortress there after 9 CE, and Bonn celebrated its 2,000th anniversary in 1989 by commemorating the construction of the first fortified Roman camp on the Rhine in 12 BCE.
Bonn is home to 20 United Nations institutions, the highest number of any city in Germany. These include the headquarters of the Secretariat of the UN Framework Convention on Climate Change, the Secretariat of the UN Convention to Combat Desertification, and the UN Volunteers programme.
Deutsche Post DHL and Deutsche Telekom, both DAX-listed corporations, have their global headquarters in Bonn. Haribo, the largest confectionery manufacturer in Europe, was founded in Bonn in 1920 and still operates a production site there, though its head office moved to Grafschaft in April 2018.