Short answers, pulled from the story.
Give Peace a Chance was recorded on the 1st of June 1969 in Room 1742 at the Queen Elizabeth Hotel in Montreal, Quebec, Canada. Recording engineer Andre Perry brought a portable setup of four microphones and a four-track tape recorder to the hotel room.
John Lennon wrote Give Peace a Chance, though the original 1969 release credited it to Lennon-McCartney. Lennon later expressed regret about this, saying the credit should have gone to Yoko Ono, who he said co-wrote it with him. Later releases by the Lennon Estate credit only Lennon.
Give Peace a Chance was released on the 4th of July 1969 in the UK and on the 7th of July 1969 in the US by the Plastic Ono Band on Apple Records. It reached number 2 on the UK Singles Chart and number 14 on the Billboard Hot 100.
Half a million demonstrators sang Give Peace a Chance in Washington, D.C., on Vietnam Moratorium Day, the 15th of November 1969. Folk singer Pete Seeger led the crowd, calling out to President Nixon and Vice President Agnew between choruses.
John Lennon sang lead vocals and played acoustic guitar, joined by Tommy Smothers of the Smothers Brothers on acoustic guitar. Yoko Ono and others provided handclaps and tambourine. Celebrities present including Timothy Leary and Petula Clark contributed backing vocals. Andre Perry handled production.
In 1991, Yoko Ono organized a new recording of Give Peace a Chance in response to the Gulf War, performed by a large group called the Peace Choir. Participants included Peter Gabriel, Lenny Kravitz, Little Richard, Tom Petty, Iggy Pop, Bonnie Raitt, Sean Ono Lennon, and dozens of others. The recording charted in multiple countries.