Short answers, pulled from the story.
The merged entity retained the name National Football League with unified rules adopted by 1970 at the latest. By 1970, three NFL teams and ten AFL teams formed the American Football Conference and National Football Conference.
Lamar Hunt conceived the American Football League in September 1959 after being rebuffed by the NFL regarding Dallas expansion. The new league had six franchises by August 1959 and grew to eight by its first opening day in 1960.
On the 8th of June 1966, collaborators announced a merger agreement in New York. Tex Schramm secretly contacted AFL owners led by Lamar Hunt about merging the leagues before this announcement occurred without knowledge of Al Davis.
When the AAFC disbanded following the 1949 season, three of its teams joined the NFL: the Cleveland Browns, San Francisco 49ers, and Baltimore Colts. These franchises brought new energy to the older league and proved that professional football could thrive outside traditional markets.
The plan called for combining 24 teams initially, expanding to 26 by 1969 and 28 by 1970. By 1970, three NFL teams and ten AFL teams formed the American Football Conference while thirteen remaining NFL teams formed the National Football Conference.