Short answers, pulled from the story.
Past Masters is a two-disc compilation album set by the Beatles, originally released on the 7th of March 1988. It collects all songs the band released commercially that were not included on their twelve original UK studio albums or the US Magical Mystery Tour LP, covering singles, B-sides, the Long Tall Sally EP, two German-language tracks, and a charity album recording.
Past Masters was compiled by Beatles historian Mark Lewisohn, who also wrote the liner notes for the original 1988 release. His name was removed from the 2009 remastered reissue.
Past Masters was originally released on the 7th of March 1988 as two separate CDs and a double cassette bundle. A vinyl double LP followed, released on the 24th of October 1988 in the US and the 10th of November 1988 in the UK.
The 2009 reissue, released on the 9th of September 2009, replaced the mono mixes of "From Me to You" and "Thank You Girl" with stereo mixes. Mark Lewisohn's name was also removed from the packaging of this remastered edition.
The Beatles recorded German-language versions of early hits for the European market. Both sides of the resulting single, "Komm, Gib Mir Deine Hand" and "Sie Liebt Dich", never appeared on any standard UK album, making them eligible for inclusion on Past Masters Volume One.
The "Wildlife" version of "Across the Universe" on Past Masters Volume Two was taken from a charity compilation album called No One's Gonna Change Our World. It is a distinct recording from the version that appeared on the Let It Be album.