None, they are alternative spellings of the same word.
You need an adaptor to play xbox live.
Yes, it will you get driver for your adapter from the adapter's manufacture website.
There is no difference.
The 3DS XL does not come with an AC adaptor. The adaptor for your country is sold seperately.
No. The person who designed your appliance had a 12v adapter, so when he designed the adapter connector he put a resistor in it to drop the voltage to 9v.
No. The adaptor will overheat.
Yes, it already has a wireless adaptor inside it.
You need an adaptor to play xbox live.
It should come with one on it, but any adapter will work, they all have the same threading.
yes you need a network adaptor
Yes, if it is a wireless USB adaptor.
Pretty certainly no; it depends slightly on the type of adaptor - if it's regulated then you'll probably destroy the adaptor and maybe the device it's plugged unto, if it's unregulated then you'll probably destroy the device and maybe the adaptor.