Short answers, pulled from the story.
The word trombone derives from the Italian tromba meaning trumpet combined with the suffix -one to indicate largeness. Court records from 1495 first documented the English term shakbusshe while Spanish sources attested to similar terminology as early as 1478.
Christoph Willibald Gluck became the first major composer to use the trombone in an opera overture with Alceste in 1767. He subsequently employed it in operas such as Orfeo ed Euridice and Iphigénie en Tauride in 1779.
Christian Friedrich Sattler originally developed this valve attachment in the late 1830s for a B tenor trombone built with wider bore dimensions. Modern instruments retain the essential design unchanged from that era.
The modern system features seven chromatic slide positions on a tenor trombone in B flat. Andre Braun first described this system circa 1795 while Joseph Fröhlich wrote about differences between the modern system and an old system using four diatonic positions in 1811.
Tenor trombones produced in France during 19th and early 20th centuries featured bores around 0.459 inches with small bells not more than 10 inches diameter. Bell sizes remain very large in all German trombone sizes exceeding 11 inches diameter.