Yes, the Nintendo eShop is free. All you need to access it is a working internet connection.
A redeem download code in the nintendo eshop is a code that you get from club nintendo, for example, then type it in the nintendo eshop to get a game.
Nintendo eShop was created on 2011-06-06.
Mario Kart 7 is already in the Nintendo 3DS eShop
Yes, it is available on the Nintendo eShop for $39.99.
It is already on the eShop for 3ds
You can download software from the Nintendo eShop. You must have internet access. It is accessible from the 3DS Home Menu.
You can only use Nintendo eShop money to buy games from the Nintendo eShop. Therefore, all other forms of currency (Club Nintendo Coins, Wii Points, DSi Points) will not work for the Nintendo eShop.
No. Because the eShop no longer uses Nintendo points, they will have their own set of prepaid cards.
Yes, Nintendo eShop uses 'real' money so $1 = 1 eShop dollar.
You need to have bought a 3DS before the 12th of August 2011, or performed the latest system update & accessed the Nintendo eShop before then.
Mario Kart 7 is not a downloadable game. It is only sold in stores, not on the Nintendo Eshop.