Short answers, pulled from the story.
John Lennon wrote the song to confound listeners who had been affording serious scholarly interpretations of the Beatles' lyrics. He later expressed dismay upon belatedly realising that the walrus was a villain in Lewis Carroll's poem The Walrus and the Carpenter.
The song is the first studio recording made by the Beatles after the death of Brian Epstein in August 1967. It reached number one on the British singles chart alongside Hello Goodbye which reached number two during December 1967.
The song ends using a Shepard tone with a chord progression built on ascending and descending lines in the bass and strings. Musicologist Alan W. Pollack analyses the chord progression as a harmonic Moebius strip with scales in bassline and top voice that move in contrary motion.
Shortly after release the song was banned by the BBC for the line Boy you have been a naughty girl you let your knickers down. This ban occurred despite the track reaching number one on the British singles chart alongside Hello Goodbye which reached number two.
The single achieved sales of over 50,000 copies in Australia being eligible for the award of a Gold Disc. Chart history shows peak positions including number one in Belgium and New Zealand and number 56 on US Billboard Hot 100.