Either hitting the Home key or clicking and holding the left mouse button to move will recenter the camera focus on the lead character.
To replace or add a skill icon on the toolbar (there are 5 you can cycle between, using the arrow buttons to the left of the slots, or the R and F hotkeys), open the skill window (hotkey K, or there is a button under the character portrait), select the skill catagory and then drag and drop the icon to a skillbar slot.
