Unlimited Secret Players:
Have about 5000 MVP Points and save your profile. Go ahead and get the Secret Players you want, place them on a team, and save the rosters. Load your profile again. The initial amount of MVP points you had will be there and the players will still be on the team you put them on.
Unlocking All Rewards:
Go Into My Mvp and create a player using the name "DAN CARTER". There will be a message confirming that you unlocked all rewards.
Thanks to Revolution readers oldskoolz and Brandon Billington!