Short answers, pulled from the story.
Hugo Riemann (the 18th of July 1849 - the 10th of July 1919) was a German musicologist and composer regarded as the leading European music scholar of his time. He coined foundational terms still used in music education, including functional harmony, the tonic, the dominant, the subdominant, and the parallel, and his theory of harmonic function remains the basis of harmonic instruction in Germany.
Riemann coined the terms functional harmony, tonic, dominant, subdominant, and parallel, which remain in everyday use. He also originated the concept of the metric and rhythmic phrase, a basic element of modern music education.
The Musik-Lexikon is a complete dictionary of music and musicians first published by Riemann in 1882. It reached a fifth edition by 1899 and was translated into English between 1893 and 1896.
Neo-Riemannian theory is a significant strand of modern music scholarship that grew out of Riemann's harmonic transformations. The American theorist David Lewin adapted those transformations, and the Tonnetz, another pillar of neo-Riemannian theory, was popularized largely through Riemann's writings even though he did not invent it.
Riemann's pupils included Max Reger, the German composer, pianist, organist, and conductor, and Walter Niemann, a musicologist and composer.
Riemann held positions in Bielefeld, Leipzig (as Privatdozent from 1878), Bromberg, Hamburg Conservatory (1881-1890), Sondershausen Conservatory, and Wiesbaden (1890-1895). He returned to Leipzig University in 1895, was appointed professor in 1901, and became Director of the Institute of Musicology in 1914.