Short answers, pulled from the story.
John Lennon spontaneously created the phrase Give Peace a chance during his stay in Room 1742 of the Queen Elizabeth Hotel on the 1st of June 1969. André Perry captured the recording using four microphones and a four-track tape recorder inside the hotel suite.
The initial release credited the song to Lennon-McCartney despite Yoko Ono's significant role because John Lennon felt guilty about giving Paul McCartney credit on his first independent single. Author Ian MacDonald suggested this decision thanked McCartney for helping record The Ballad of John and Yoko quickly. Later releases curated by the Lennon Estate removed McCartney from the credits entirely.
The single was released on the 4th of July 1969 in the United Kingdom and reached number two on the British singles chart. It arrived in the US on the 7th of July 1969 where it peaked at number fourteen on the Billboard Hot 100.
Half a million demonstrators sang the song during Vietnam Moratorium Day in Washington DC on the 15th of November 1969. Pete Seeger led the crowd while interspersing phrases like Are you listening Nixon between choruses.
Yoko Ono recorded a new version in 1991 featuring artists like Amina Adam Ant and Peter Gabriel under the name Peace Choir. Digital remixes appeared exclusively on Beatport starting the 1st of June 2008 with newly recorded vocals by Yoko Ono.