Short answers, pulled from the story.
The seven men chosen for Project Mercury were Scott Carpenter, John Glenn, Gordon Cooper, Gus Grissom, Walter Marty Schirra, Alan Bartlett Shepard, and Donald Kent Slayton. These individuals were drawn from military test pilot records to meet strict civil service job specifications issued by NASA.
NASA announced the final selection of the seven astronauts on the 9th of April 1959 during a press conference in Washington DC. This announcement followed months of psychological evaluations and physical tests conducted at the Lovelace Clinic between January and March 1959.
Candidates had to be military test pilots with grades ranging from 12 to 15 and salaries between $8,330 and $12,770 annually. The three-man panel restricted the pool to active duty officers from the Air Force, Navy, Marines, and Army who met rigorous medical and mental fitness standards.
Each astronaut received $71,428.71 from an exclusive contract negotiated by agent C. Leo DeOrsey between August 1959 and the 15th of May 1963. They shared these proceeds equally regardless of which individual flew first or how many missions they completed.
John Glenn served as a Democratic U.S. Senator from Ohio from 1974 to 1999 and later flew on STS-95 mission in October-November 1998 at age 77. He held the record for the oldest person to orbit Earth until his death in 2016 at age 95.