Short answers, pulled from the story.
North American Aviation produced the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F-86 Sabre jet fighter, the X-15 rocket plane, the XB-70 Valkyrie bomber, and the Space Shuttle orbiter, among others. The company also built the Apollo command and service module and the S-II second stage of the Saturn V rocket.
Clement Melville Keys founded North American Aviation on the 6th of December 1928, initially as a holding company that bought and sold interests in airlines and aviation-related companies. The Air Mail Act of 1934 forced it to reorganize as a manufacturing company.
A Royal Air Force suggestion to replace the P-51's Allison engine with a Rolls-Royce Merlin engine transformed the aircraft's performance. This change is described as possibly one of the most significant events in Second World War aviation, turning the Mustang into what many consider the best American fighter of the conflict.
Employment at North American dropped from a peak of 91,000 to 5,000 in 1946, and orders fell from 8,000 aircraft on V-J Day to just 24 shortly after. General Motors divested the company as a public company in 1948, and North American rebuilt itself around new aircraft designs and eventually the space program.
North American merged with Rockwell-Standard in September 1967 to form North American Rockwell, which renamed itself Rockwell International in February 1973. Rockwell International's defense and space divisions, including Autonetics and Rocketdyne, were sold to Boeing in December 1996.
North American Aviation was the prime contractor for the Apollo command and service module and built the S-II second stage of the Saturn V rocket. The company built the Command and Service modules for all 11 Apollo missions, beginning after CEO Lee Atwood committed the company to the space program in 1960.