I like the team logo concepts so far, and can't wait to see uniforms.
Why not suffix the names of the teams with e.g. AFC (American Football Club) or GFC (Gridiron Football Club), in the vein of a lot of sports teams in Europe and South America? The city name by itself isn't sufficient enough to name the team, I wouldn't think.
As for the league logo, maybe a partially laced football, with the laces that are present forming a cross shape?