I've already created my Minecraft skin and saved it on the SD card, but how can I download things from the SD card to the Wii-U now? And then on Minecraft Wii-U Edition?
In my experience that doesn't work at all, you have to buy the skins in the shop, it's only free on PC.
But I can generally also load things from the SD card onto the Wii-U
Pictures should go, but basically no, according to my information.
No that doesn't work. So it is possible through the Homebrew Launcher (Hacking Platform) to load files onto your Wii you and in general to get more out of your Wii U. But this is not possible from the factory!