It depends on what you want to do. If you update, you'll miss out on future software exploits but you'll be able to go online, or you could wait for something like emunand which would give you the benefits of a later firmware while keeping sysnand on an earlier one. There is that new method to...
You should get a nand backup from the Dsiware downgrade, so you should be able to format then restore all of your data with Decrypt9 at the end of the guide.
It kind of depends on what you want to do. If you want the mod to be permanent, you can use wupclient to transfer mod files from your SD card to the USB or nand. This is the best method because you don't have to do anything before booting the game. If you want mods to be temporary, use Cafiine...
No. You'll need a second system with custom firmware or a hardmod to downgrade from 11.2. Downgrading from 11.2 without either of those things isn't going to happen for a while.
Nintendo told everyone with a review copy to not go online, and you could call or email Nintendo and prove you got a review copy. They might remove your ban if you do that.
If there was a way to boot into wupserver you wouldn't be bricked because you could just boot into rednand which would mean coldboothax installed successfully. The brick completely blocks you out of sysnand, so even if you could boot a sysnand fw.img it would try booting the DS title again.
It is permanent. The only time you would need to run CFWbooter is if you installed a game with a fake ticket and have to use sig patches to play it. You don't need to run it if you install a game that's available as a disc.
You'll need a valid ticket to use it in sysnand without sig patches, but you can install the normal game then transfer the mod files from SD to USB using wupclient which will allow you to use it on sysnand without sig patches.
How is that a contradiction? It freezes for me before my PC is connected which means that it's a problem on the Wii U's side, not a problem with Python.
I've used it with files over 4gb and I haven't had any problems. It sometimes freezes randomly and it usually happens to me before I connect my PC.
Weird. I haven't seen this issue before. Do you have Python installed? If it is installed, try typing C:\Python27\python.exe -i wupclient.py
Hold shift and right click in the directory where wupclient.py is located. Select open command window here. Run the wupserver fw.img on your Wii U, then type in python -i wupclient.py and press enter. You should be connected to your Wii U after that.