I don't get into the all-time teams. When you have high rated players(10-15 90+ players) the game doesn't play as good. To me anyway. I tried to rate the players as realistic as possible. For instance, all the Gene Stallings teams have low rated pass lockers. The 92 team is the exception to the rule with the high rated players on defense. I don't think there is but 1 (David Palmer) offensive guy rated high.
As far as the limit on teams, you can create as many as you want. You can only download 12 but you can purchase a special download that allows you to dl 120 teams.