While you are in the park, you have a photopass card. Get as many pics taken as you can or want. After you get home, you go to your account, type in the number from the back of your card the pictures are then loaded. YOu can edit them anyway you want to, ie borders, year, etc. It will be mailed to you once you are finished. We did this last September and was very pleased. Thats why I really wanted to find it again for this trip

You don't take anything to WDW to show proof. You will have a comfirmation email with instructions for after you are home. Just don't delete it.