1. Are there hotkeys for attacking and casting spells?
Not coded into the game by default, no. The actions were designed to be executed with a mouse in mind.
2. What skill is equivalent for spears? Just got a level up and not sure what to focus on with the fighter, who has a spear.
There isn't one (as to the why, this becomes evident when you realize that the spear you can acquire from the Skeleton Warriors is the ONLY spear you'll find in the game).
If your fighter character is on the front line, be ready to ditch the spear for something like a sword or (the somewhat less reliable) axe.
If attacking from the back row is a priority, putting points into the Assassination skill should be the focus (which would also eliminate the need for the spear entirely).