No football is only in America
No. The NFL and college football are played in the fall, but the Arena Football League and smaller indoor football leagues play in the spring and early summer.
I can think of Robbie Earnshaw. Not only has he played in all leagues, he has scored hattricks in all divisions...but there must be more players
No. The Canadian Football League - which is older than the NFL - is a good draw in Canada and small gridiron football leagues exist in other countries.
That would be Denis Law of Manchester United and Scotland.
No player is worst in football, it is only the luck and skills that matters.