Just an update...
Further testing has shown you *can* create new hotkeys for skills/potions/weapons without causing the game to crash.
Once you've created 12 new hotkeys by overwriting the original F1-12 key assignments, you can reassign F1-12 to different skills etc. while keeping your newly modified hotkeys.
So potentially you could continue overwriting F1-12 and have a hotkey for everything - as long as you have enough unused keys left on your keyboard.
I hope this is useful to some of you.
