Short answers, pulled from the story.
"Paperback Writer" was written primarily by Paul McCartney and credited to the Lennon-McCartney partnership. John Lennon confirmed in a 1972 interview with Hit Parader that it was mainly McCartney's tune and that he may have helped with some of the lyrics.
"Paperback Writer" was released in the United States on the 30th of May 1966 by Capitol Records, with catalogue number 5651. The UK release followed on the 10th of June 1966 on Parlophone, with catalogue number R 5452.
McCartney said the song was inspired by a challenge from his Aunt Lil, who asked why he always wrote about love. Radio Luxembourg DJ Jimmy Savile recalled that the specific trigger was McCartney seeing Ringo Starr reading a book backstage at a concert. A 2007 New Yorker account added that McCartney may have been influenced by reading a Daily Mail story about an aspiring author, "possibly Martin Amis."
"Paperback Writer" reached number 1 on the US Billboard Hot 100 for two non-consecutive weeks. It replaced the Rolling Stones' "Paint It Black" and was briefly displaced by Frank Sinatra's "Strangers in the Night" before returning to the top spot. The Recording Industry Association of America certified it gold on the 14th of July 1966.
The British single was promoted with a photograph of the Beatles draped in raw meat and decapitated baby dolls. The same image was briefly used as the cover of the American album Yesterday and Today, where it became known as the "butcher cover." An advertisement using the photograph also appeared on the cover of Disc and Music Echo with the caption "Beatles: What a Carve-Up!"
McCartney played a Rickenbacker bass, and the engineering team amplified its sound by positioning a loudspeaker directly in front of the bass cabinet. The moving diaphragm of the second speaker generated the electrical signal that was recorded. Engineer Geoff Emerick described it as the first time the bass sound had been heard in all its excitement on a Beatles record.