The numbers are underneath a scratchable layer, you scratch it off to reveal it, then enter the code.
No
At Game Stop.
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.
Yes, 3DS that are bought have eShop preinstalled.
No, you have to purchase the games with eShop money.
The content will go on your SD card.
No. As with 3DS games, prepaid cards are region locked. You cannot redeem a prepaid card bought in the US on the European eShop.
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.
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
Nintendo eShop prepaid cards can be bought wherever you can buy Wii U or Nintendo 3DS games. Example of this include Future Shop, Best Buy and EB Games. It is also important to ensure that the card you are buying is an eShop prepaid card. Wii points or Nintendo DSi points cards cannot be redeemed on a Wii U. On the other hand, older eShop prepaid cards branded as "Nintendo 3DS" prepaid cards can be used on the Wii U eShop.
The eShop for the Nintendo 3DS is out already.