Short answers, pulled from the story.
Giovanni Battista Martini, known as Padre Martini, was an Italian Conventual Franciscan friar born in Bologna on the 24th of April 1706. He was one of the leading musicians, composers, and music historians of his era, and a mentor to Wolfgang Amadeus Mozart, Johann Christian Bach, and a range of other prominent composers.
Martini was appointed chapel-master at the Basilica of San Francesco in Bologna in 1725 at age nineteen. His compositions attracted attention, and he subsequently established a composition school at the invitation of amateur and professional friends. In 1758 he was also invited to teach at the Accademia Filarmonica di Bologna.
Martini's pupils included Wolfgang Amadeus Mozart, Johann Christian Bach, the Belgian composer André Ernest Modeste Grétry, the Bohemian Josef Mysliveček, the Ukrainian Maksym Berezovsky, and the Italian cellist Giovanni Battista Cirri. His fellow Franciscan friar Stanislao Mattei also studied with him and succeeded him as conductor of the girls choir.
Martini was a zealous collector of musical literature. Charles Burney estimated his library at 17,000 volumes. After Martini's death in 1784, a portion passed to the Imperial library at Vienna, while the rest remained in Bologna and is now held at the Museo Internazionale della Musica.
The Storia della musica was Martini's major historical work, published in Bologna between 1757 and 1781. Three volumes appeared, all treating ancient music, representing only a fragment of his intended plan. The work was noted for immense reading and industry, though critics described its style as dry and overloaded with material not strictly historical.
Leopold Mozart consulted Martini regarding the talents of his son Wolfgang Amadeus Mozart. After visiting Bologna, the younger Mozart wrote to Martini in very effusive terms. Mozart is listed among Martini's pupils alongside Johann Christian Bach and other leading composers of the period.