Short answers, pulled from the story.
NASA Astronaut Group 4 was a cohort of six astronauts selected in June 1965, the first group chosen on the basis of research and academic credentials rather than test pilot experience. They were nicknamed "The Scientists" because a doctorate in the natural sciences, medicine, or engineering was a prerequisite for selection.
A total of 1,351 applications were received by the deadline of the 31st of December 1964. The National Academy of Sciences reviewed 400 of those applicants on academic grounds and reduced the field to fifteen finalists, from whom six were ultimately selected.
Harrison H. Schmitt, a geologist with a PhD from Harvard, walked on the Moon during Apollo 17 in December 1972. He became the twelfth person to walk on the lunar surface and the last scientist ever to do so.
Owen K. Garriott, Edward G. Gibson, and Joseph P. Kerwin all flew on Skylab missions, each serving as the Science Pilot on their respective crews. Garriott later flew a second spaceflight on STS-9 in November 1983.
Duane Graveline resigned in August 1965 after his wife filed for divorce, and NASA demanded his departure to avoid a scandal. F. Curtis Michel resigned in September 1969 after prime and backup crew selections for Apollo 13 and Apollo 14 excluded Group 4 members entirely, filling the slots with pilot astronauts from the 1966 group.
Members who were not already qualified pilots completed 55 weeks of flight training at Williams Air Force Base in Arizona. All six then underwent a shared curriculum including 154 hours of astronomy, 112 hours of geology, and field trips to sites such as the Grand Canyon, Meteor Crater, and Philmont Scout Ranch, along with survival training in Panama, Nevada, and Pensacola.