Short answers, pulled from the story.
Otello had its world premiere at the Teatro alla Scala in Milan on the 5th of February 1887. The conductor was Franco Faccio, with Francesco Tamagno in the title role, Victor Maurel as Iago, and Romilda Pantaleoni as Desdemona.
The libretto was written by Arrigo Boito, based on Shakespeare's play Othello. Boito collaborated closely with Verdi over several years, with drafts beginning around 1879 and the final text completed in late 1886.
The project took roughly eight years from when Boito began drafting the libretto around 1879 to the premiere in 1887. Actual composition was concentrated in three short bursts: Genoa in March 1884, Genoa from December 1884 to April 1885, and Sant'Agata from mid-September to early October 1885. Verdi declared the opera finished on the 1st of November 1886.
A newspaper report appeared to suggest that Boito, himself a composer, wanted to set the Otello libretto himself. Verdi was shaken and offered to return the manuscript without resentment. Boito immediately wrote to Verdi insisting that the opera was "predestined" for him alone, which helped persuade Verdi to continue.
Otello was first performed in the United States at the Academy of Music in New York on the 16th of April 1888. The UK premiere followed on the 5th of July 1889 in London.
"Chocolate" was the project's informal code name during the years of composition. It is believed to derive from a Christmas tradition in which Ricordi sent Verdi a cake decorated with a figure of the Moor molded in chocolate, which he did three years in a row to keep the project quietly alive.