Short answers, pulled from the story.
"Dear Prudence" was written about Prudence Farrow, the sister of actress Mia Farrow. While at Maharishi Mahesh Yogi's ashram in Rishikesh in early 1968, Farrow became so absorbed in meditation that she refused to leave her bungalow for days, prompting John Lennon and George Harrison to write the song as a way of coaxing her outside.
"Dear Prudence" appears on the Beatles' 1968 double album The Beatles, also known as the White Album. It was sequenced as the second track on side one and released by Apple Records on the 22nd of November 1968.
Ringo Starr did not play drums on the main recording of "Dear Prudence". He had temporarily left the band in protest at Paul McCartney's criticism of his drumming on "Back in the U.S.S.R.", so McCartney played drums in his place during the sessions at Trident Studios in late August 1968.
Lennon used a finger-picking method known as clawhammer picking, sometimes called the Carter Family finger style. He learned the technique from singer-songwriter Donovan while the two sat beneath a jacaranda tree at the ashram in Rishikesh, and Donovan recalled that Lennon mastered it in just two days.
Siouxsie and the Banshees reached number 3 on the UK Singles Chart with their 1983 cover of "Dear Prudence". The single was recorded partly in Stockholm in July 1983 and kept from the top of the charts by Culture Club's "Karma Chameleon".
Prudence Farrow said she was "flattered" by the Beatles' gesture and called it "a beautiful thing to have done". In a 2013 interview she said she was relieved to find the song generous in spirit, unlike Lennon's more negative White Album tracks about the Rishikesh experience. She later titled her 2015 autobiography after the song.