You replied to someone asking if the game was worth it for the price. You have no idea if they have prime or not so adding in the shipping charge doesn't make much sense to me. The question was whether the game was worth it for $16 or $17 (not sure what it was going for at the time.)...
Not sure if it said it last time, but this time it's described as coming in a white box. If anyone needs this in retail packaging, I'm sure you can find it at retail price somewhere.
That was to extend the free trial by 30 days. If you went to the main page and clicked the banner for the dlc, it would take you to a page where you choose xbox or ps3.
Your link just talks about how you can't overwrite saves. Every bit of info I dig up all points to buying a device that can wipe the data from the cartridge, but that has to be done each time you'd like to start over. I don't see any way to unlock it and re-write at will.