I have browsed the net for a while but can't locate information on how to use the quad UDOO (latest ubuntu os) with an external USB WIFI dongle
You can do it for sure. Just install the appropriate firmware for your dongle and you're good to go. To know which firmware you'll need, plug your wi-fi adapter and type Code: lsusb Then google the results and install appropriate firmware with apt-get Let me know if you need additional help