The control settings have the function keys mapped. Can you use them for skills or spells, and if so, how?
Yes you can!
The system works pretty much in an identical manner to Diablo II if you've ever played it.
In order to assign abilities to a function key, expand your secondary abilities (abilities used on right click) by clicking on the ability icon on the right hand side of your action bar, hover over the ability you wish to assign, and press the function key you wish to assign that ability to.
In this instance I have F1 and F2 assigned to Magma Spear and Magma Mace respectively.
Pressing F1 makes Magma Spear the ability that is used when I right click, pressing F2 makes Magma Mace the ability that is used when I right click.