Short answers, pulled from the story.
Paul McCartney conceived the entire album concept and specific song idea during a flight returning to England from Kenya in November 1966. John Lennon attributed the core idea solely to McCartney, though the official credit remains Lennon, McCartney.
Work on the track began at Abbey Road's studio 2 on the 1st of February 1967 with George Martin producing and Geoff Emerick engineering. The group completed the recording after three further sessions by the 6th of March 1967.
The original version sits in G major and utilizes a time signature common to rock music of the era. A horn quartet filled out the instrumental sections with players like Neill Sanders and James W. Buck on French horns.
EMI released the album containing this song in the UK on the 26th of May 1967 and in the US on the 2nd of June 1967. Capitol Records distributed the single in the US on the 14th of August 1978, reaching number 71 on the Billboard Hot 100 chart.
The Beatles never performed this song live during their active years as a group. Three former members joined Eric Clapton to play it at Clapton's wedding party on the 19th of May 1979.