Short answers, pulled from the story.
The Green Bay Packers have won the most NFL championship titles with 13, nine from the pre-Super Bowl era and four Super Bowls. The Chicago Bears are second with nine total championships, and the New York Giants are third with eight.
The NFL held its first playoff game at the end of the 1932 season, played indoors at Chicago Stadium on a shortened 80-yard dirt field because of winter weather. Beginning in 1933, the league introduced a scheduled annual championship game between the winners of its two divisions.
The first NFL championship trophy was called the Brunswick-Balke Collender Cup, awarded only once, to the Akron Pros in 1920. Starting with the 1934 championship game, the winning team received the Ed Thorp Memorial Trophy, named after referee and sporting goods dealer Ed Thorp.
The Pottsville Maroons were suspended by the league for playing an unauthorized game against a non-NFL team, allowing the Chicago Cardinals to schedule additional wins and pass them in the standings. The Cardinals were offered the title but refused it, leaving the 1925 championship vacated. The Bidwill family claimed it for the Cardinals only after purchasing the team in 1933.
The AFL-NFL merger was announced on the 8th of June 1966 and became fully effective in 1970, at which point the Super Bowl became the sole NFL championship game. The former NFL Championship Game was renamed the NFC Championship Game, and the former AFL Championship Game became the AFC Championship Game.
Three permanent rule changes came out of the 1932 NFL championship, played indoors at Chicago Stadium on a shortened 80-yard dirt field. Goal posts were moved to the goal line and hash marks became mandatory for every play start. Forward passes were also made legal from anywhere behind the line of scrimmage rather than five yards back.