Short answers, pulled from the story.
The American edition was published by Scribner's on the 5th of January 1886, four days before the UK edition appeared from Longmans. Scribner's initial print run was 3,000 copies, only 1,250 bound in cloth.
Within six months of publication, close to 40 thousand copies had sold in Britain. By 1901, sales in the United States alone were estimated at over 250,000 copies.
Several sources shaped the novella. Stevenson had long been interested in divided personalities, drawing on the real case of William Brodie, an Edinburgh city councillor who secretly led a life of burglary. His friendship with Eugène Chantrelle, a French teacher executed for poisoning his wife in May 1878, also contributed. A vivid dream supplied the central plot idea of a voluntary transformation becoming involuntary.
Stevenson wrote the novella in Bournemouth, a southern English seaside town where he had moved in 1884. His stepson Lloyd Osbourne recalled that the first draft took no more than three days, and Stevenson rewrote it after criticism from his wife in three to six days.
The phrase refers to a person who displays an outwardly good nature but is sometimes shockingly evil in private. It entered everyday vernacular following the success of Stevenson's 1886 novella.
There have been over 120 stage and film adaptations of the novella. Stage adaptations began in Boston and London immediately after the 1886 publication. A musical by Frank Wildhorn, Steve Cuden, and Leslie Bricusse followed in 1990, and several video games have also been based on the story.