Short answers, pulled from the story.
Stuart Sutcliffe was a British painter and musician from Edinburgh, Scotland, who served as the original bass guitarist of the Beatles. He joined Lennon, McCartney, and Harrison in May 1960 and left the group in July 1961 to study painting in Hamburg under Eduardo Paolozzi.
Sutcliffe and John Lennon are credited with inventing the name "Beetles", inspired by their shared admiration for Buddy Holly's band the Crickets. Lennon then adapted it to "The Beatles", incorporating the word "beat", with the final version settled during an afternoon in the Renshaw Hall bar alongside Lennon and Cynthia Powell.
Astrid Kirchherr was a Hamburg photographer whom Sutcliffe met at the Kaiserkeller club while the Beatles were performing there. The two became engaged in November 1960, exchanging rings in the German custom. Kirchherr rode with Sutcliffe in the ambulance when he collapsed for the final time on the 10th of April 1962.
Sutcliffe died on the 10th of April 1962 in an ambulance in Hamburg before reaching the hospital. The cause was a cerebral haemorrhage, specifically a ruptured aneurysm resulting in severe bleeding into the right ventricle of the brain. He was 21 years old.
Paolozzi, who taught Sutcliffe at the Hochschule fur bildende Kunste Hamburg after Sutcliffe won a postgraduate scholarship in July 1961, wrote a report stating: "Sutcliffe is very gifted and very intelligent. In the meantime he has become one of my best students."
Sutcliffe plays bass on three songs included in the Beatles' 1995 compilation Anthology 1, all recorded in 1960: "Hallelujah I Love Her So", "You'll Be Mine", and "Cayenne". In 2011, his estate released a recording claimed to be Sutcliffe singing Elvis Presley's "Love Me Tender", reportedly recorded in 1961 and donated to the estate in 2009.