Code goes only in the German PSN account after it has been redeemed, you can also load the DLC only with the German disc. With a US import can be the DLCs neither invite nor play (after they have been loaded with German Disk).
Not even the costumes / masks etc, or Grounded mode can be played with a US disk. Therefore deducting a star because only dransteht that you need a German PSN account, not that you need a German disc.
So if you are a US import has, you should not buy that, but the things you have to buy separately in the US store, because there is no Season Pass more.
With German disk but you should access, even if you do not want the costumes or map packs, Left Behind and the Grounded Mode you should not miss.