Short answers, pulled from the story.
W. S. Gilbert was born on the 18th of November 1836 and Arthur Sullivan was born on the 13th of May 1842. Both men were born in London and brought vastly different backgrounds to their theatrical partnership.
The partnership between W. S. Gilbert and Arthur Sullivan began in 1870 and produced fourteen comic operas between 1871 and 1896. Their first true spark of collaboration was Thespis, which was produced at the Gaiety Theatre in 1871.
The Mikado is the most frequently performed Savoy Opera by W. S. Gilbert and Arthur Sullivan. It opened in 1885 and ran for 672 performances at the Savoy Theatre.
The working relationship between W. S. Gilbert and Arthur Sullivan ended in 1890 due to a disagreement over the expenses of a new carpet for the Savoy Theatre lobby. The conflict escalated when Arthur Sullivan supported Richard D'Oyly Carte in a legal dispute, leading to a final break in 1898.
Arthur Sullivan died in 1900 and W. S. Gilbert died in 1911. Gilbert was knighted during the first repertory season of the Savoy Theatre in 1906 and assisted Mrs. Carte in staging two repertory seasons between 1906 and 1909.