Short answers, pulled from the story.
Wolfgang Amadeus Mozart began work on the unfinished opera Lo sposo deluso in 1783. The project started with a libretto written by Giuseppe Petrosellini for another composer, Domenico Cimarosa.
Musicologist Neal Zaslaw suggests the abandonment resulted from difficulties adapting the libretto for Viennese audiences. Another theory points to the arrival of Lorenzo Da Ponte's libretto for Le nozze di Figaro in 1785.
Constanze Mozart arranged for the overture and opening quartet to be performed during a concert featuring their youngest son, Franz Xaver Mozart at the Estates Theatre in Prague. The identity of the arrangers who orchestrated these two pieces remains unknown.
Francesco Benucci was cast as Bocconio Papparelli while Nancy Storace played Eugenia and Stefano Mandini took the role of Don Asdrubale. Katherina Cavalieri portrayed Bettina and Francesco Bussani sang Pulcherio alongside Signore Pugnetti playing Gervasio and Therese Teyber assigned the role of Metilde.
Only twenty minutes of music from Lo sposo deluso survive today within Act One. These five numbers constitute the only extant musical content from the opera including an upbeat overture, a quartet, two aria fragments, and a terzetto.