i already used the code from the pack i got from game going to try and see if this one is going to work. don't see any reason why it shouldn't work.
Not on the same account you ain't.
pre order pack. got one already from game so in total i'm getting Ł10 discount from psn.
What's that box on top of the console box?
You have to go through a registration process and sign in with your PSN ID, then select the game you want (I'd suggest Escape Plan, as it reaps the highest discount), then the guys at Sony will sent you a PSN discount code via email.