The thing is, this page says that the 8 pins are an USB connector so I guess I couldn't use that with arduino ? There is this Bus Interface: USB 2.0 (8-pin header).
The other thing is, I imagine if I plug that into a computer (with an USB adaptor), then it would simply make a wifi dongle ?
Well I have never seen printer Wireless Card that uses something different than USB or PCI connection. Your card will be USB for sure, so you cant use it with Arduino easily.
You may be able to use it with PC.
But remember that most of these modules uses 3,3V supply, not 5V as regular USB power line!
I noticed that there are even USB pins silk screened on PCB.