Short answers, pulled from the story.
The first performance of Così fan tutte took place on the 26th of January 1790. Wolfgang Amadeus Mozart conducted this initial showing which marked the culmination of his collaboration with librettist Lorenzo Da Ponte.
Recent evidence suggests Antonio Salieri may have attempted to set the same text before leaving it unfinished rather than Emperor Joseph II directly commissioning the work. Scholar John Rice discovered two terzetti by Salieri within the Austrian National Library in 1994 indicating a competitive environment among composers for court commissions during that era.
The opera received only five performances before the run stopped due to the death of Emperor Joseph II. Court mourning protocols prevented further shows until June 1790 when Mozart returned to conduct a second performance.
Mozart specified woodwinds including two flutes, two oboes, two clarinets, and two bassoons alongside brass sections featuring two horns and two trumpets. String forces comprised first violins, second violins, violas, violoncellos, and double basses while harpsichord and violoncello provided basso continuo for secco recitatives.
A British premiere finally took place at the King's Theatre in London in May 1811 after Viennese audiences initially accepted the subject matter without offense in 1790. American audiences waited until 1922 to see the work performed at the Metropolitan Opera.