eShop codes can be purchased at game retailers such as GAME. They come in the form of a card with a scratch-off layer that reveals the code.
No.
Yes, 3DS that are bought have eShop preinstalled.
No, you have to purchase the games with eShop money.
The eshop. The eshop is the 3DS's version of the wii shop channel. (please note that the eshop will not be available until 2011 late May)
It is already on the eShop for 3ds
The eShop for the Nintendo 3DS is out already.
In order to add funds on the Nintendo eShop, you can either connect your credit card and withdraw cash from there, or you can buy a prepaid point card which can be redeemed by entering the pin afterwards.
The numbers are underneath a scratchable layer, you scratch it off to reveal it, then enter the code.
It doesn't really matter, but probably best to put your own. The eShop's region is determined by the region of your 3DS anyway.
Using the Nintendo eShop.
No
The 3DS will connect to the Nintendo eShop for the region selected, regardless of the actual location of the 3DS. Therefore, if you set the German 3DS to the UK (since you set it in English), it will be connected to the UK's eShop. Therefore, you will not be able to access or buy German games unless you change the region.