Short answers, pulled from the story.
The Mercury Seven were Scott Carpenter, Gordon Cooper, John Glenn, Gus Grissom, Wally Schirra, Alan Shepard, and Deke Slayton. NASA publicly announced their selection on the 9th of April, 1959. They were chosen from a pool of 508 military test pilots and created a new profession in the United States.
NASA announced the Mercury Seven on the 9th of April, 1959, at a press conference in Washington, DC. Two hundred reporters attended the event. Time magazine immediately compared the seven to Columbus, Magellan, Daniel Boone, and the Wright brothers.
Slayton was grounded because doctors detected an atrial fibrillation, an erratic heart rhythm, before his scheduled Mercury flight. He remained with NASA in management roles, serving as Director of Flight Crew Operations. He was restored to flight status in July 1970 and finally flew in space in July 1975 on the Apollo-Soyuz Test Project.
In August 1959, agent C. Leo DeOrsey negotiated a $500,000 exclusive contract between the Mercury Seven and Life magazine, granting the publication access to the astronauts' private lives, homes, and families. Between August 1959 and the 15th of May, 1963, each astronaut received $71,428.71 from the arrangement.
All seven Mercury astronauts eventually flew in space. As a group they participated in all four NASA human spaceflight programs of the 20th century: Mercury, Gemini, Apollo, and the Space Shuttle. Gus Grissom, who flew both Mercury and Gemini missions, died in 1967 before the Apollo program's crewed flights began.
Glenn flew on Space Shuttle Discovery on mission STS-95 in 1998 and, at the age of 77, became the oldest person to orbit Earth at the time. He was a sitting U.S. senator from Ohio when he flew, and the only member of the Mercury Seven to fly on the Space Shuttle. He died in 2016 at the age of 95, the last surviving member of the group.