The PIN is a room only discount. You can add tickets and dining to your reservation, but they will be at full price. If you buy the 5 day ticket to take advantage of the gift card offer, I think, the only way you would be able to use those tickets at a later time (december) is to add the non-expiration option to your tickets and I honestly have no idea what that cost is. There is a 'sticky' on the theme parks boards that has any and all information you need on tickets. I have never added the non-expiration option to our tickets, but I am sure the specific pricing is there.
HTH