Short answers, pulled from the story.
Project Gemini was designed to develop the spaceflight techniques required to support the Apollo Moon landing program. Its specific objectives included proving that humans could survive at least eight days in space, demonstrating orbital rendezvous and docking with another vehicle, and showing that astronauts could perform useful extravehicular activity outside the spacecraft.
Sixteen individual astronauts flew on 10 crewed Gemini missions during 1965 and 1966. The program also included two uncrewed test flights in April 1964 and January 1965.
Jim Chamberlin was the chief designer of the Gemini capsule. He had previously served as chief aerodynamicist on the Avro Canada CF-105 Arrow program and joined NASA along with 25 senior Avro engineers after that Canadian program was canceled.
Gemini 6A and Gemini 7 flew simultaneously in December 1965 and accomplished the first space rendezvous. The two craft held station-keeping at distances from 1 to 300 feet for more than five hours. Gemini 7 also set a 14-day endurance record on that flight.
Project Gemini cost $1.3 billion in 1967 dollars from 1962 to 1967. A January 1969 NASA report to Congress itemized $797.4 million for spacecraft, $409.8 million for launch vehicles, and $76.2 million for support.
Gemini capsules are displayed at museums across the United States. Gemini IV and Gemini VII are at the National Air and Space Museum in Washington, D.C. Gemini III is at the Grissom Memorial in Spring Mill State Park in Mitchell, Indiana, and Gemini XII is at the Adler Planetarium in Chicago.