Short answers, pulled from the story.
John Lennon and Paul McCartney wrote the track years before forming the Beatles. McCartney composed the verse and chorus while Lennon contributed the middle eight section. A bluesy dry harmonica riff opens the track, played by Lennon.
The second attempt took place on the 4th of September 1962 with Ringo Starr replacing Best. It became the original Parlophone single pressing released on the 5th of October 1962. Early pressings featured a red Parlophone label with Ringo Starr playing drums.
Martin instructed McCartney to sing the words love me do so Lennon could start playing on the word do. The arrangement changed in the studio when producer George Martin realized the harmonica clashed with the vocals. This decision allowed Lennon to focus on his harmonica part after McCartney sang the opening lines.
Three distinct recording attempts exist for this debut single. The first session occurred on the 6th of June 1962 featuring Pete Best on drums. A third session happened one week later on the 11th of September 1962 where session drummer Andy White played drums while Starr handled tambourine duties.
Australia saw it hit number one on the 14th of February 1964. New Zealand placed it at the top of their chart on the 4th of June 1964. It also ranked as the fourth Lennon-McCartney composition to top the US charts in 1964.