During a season, go to "Settings" and turn salary caps off. Then, go to "Manage Roster", and make or edit a player. You can put all their stats to 100.
Extra teams and stadiums
Keep collecting cards until you get some stadiums and teams.
Ledgendary Players
The way to get the extra charater is to that you have to make a profile. After you make a profile then you must play lots of game with your profile on. After you get a least 40 tokens you can by a pack of 15 cards. If you get lucky you might get one of the ledgendary players. Some of the players are John Elway, Reggie White, and many more of them.
Random team selection
Select exhibition mode. Press L to choose a random visiting or R to get a random home team at the team selection screen.
Skip coin toss
Repeatedly press A + Start + Z (about five to six times) at the coin toss screen to advance to the kickoff.