As you mentioned you late used Linux there are easy ways.
The network-manager (both Gnome and KDE use it) allows you to set up your N9 as Internet connection. Just choose synchronize and connect when you plug it in.
You may have to google your APN. I can show you my configuration if you have problems.
The connection will be saved, so its just a click away if you plug your phone again.

To create a hotspot is equally easy.
For example: http://www.howtogeek.com/116409/how-...-access-point/
Under KDE you also just create a new connection Wireless, IP4 shared to other computers.

No console work necessary.
At least under KDE you can even choose to enable the two connections together so you hotspot is always just a click away.