Who became MLB's first Black manager, with Cleveland in 1975?

Who founded the Negro National League in 1920? Which Negro Leagues star was famed as perhaps the fastest player in baseball history? Which Negro Leagues player and manager later became MLB's first Black coach, with the Cubs in 1962? Which Dodgers executive signed Jackie Robinson? How far is the pitching rubber from home plate? How many games does each MLB team play in a regular season? In which year did the American League adopt the designated hitter? In which year did MLB introduce the pitch clock?