Short answers, pulled from the story.
Emperor Joseph II banned the play because it contained objectionable content and frank class conflict that made authorities nervous about its potential impact on society. He ordered the Censor to either reject the piece or make alterations so he would be responsible for the performance.
Lorenzo Da Ponte turned Beaumarchais's French comedy into a libretto in six weeks during 1785. He rewrote the entire work in poetic Italian while stripping away dangerous political undertones to gain imperial approval.
The Marriage of Figaro premiered at the Burgtheater in Vienna on the 1st of May 1786. Wolfgang Amadeus Mozart conducted the first two performances while seated at the keyboard following the custom of the day.
The finale of act 2 lasts approximately 20 minutes and stands as one of the longest uninterrupted pieces of music Mozart ever composed. Eight of the opera's eleven characters appear on stage during its more than 900 bars of continuous music.
Francesco Benucci portrayed Figaro in the premiere cast that included Stefano Mandini as Count Almaviva and Nancy Storace played Susanna. Modern performance practice usually assigns the role of Figaro to a bass-baritone singer.