Area effect spells and line of sight Options

[Shrike30]

This topic has nothing to do with trying to drop AE spells on people around the corner down a hallway :P

Our mage decided the other day that the most effective way he had of neutralizing a bunch of people in the same elevator he was in was stunball. Anybody he could see, obviously, was a valid target. In our games, we've ruled that the CASTER is also a valid target because he's got LOS to his own aura, which surrounds him.

The oddball questions come from how, exactly, Line of Sight is defined.

Can he protect his sammie buddy in the elevator by having the sammie stand behind him, where he can't "see" him but you can draw LOS on the Astral (and in real life, actually)?

Is your "LOS" just a cone that extends from your eyes outwards, or does it radiate from them in a sphere (keeping with the eyes being the center of LOS prevents things like sticking your hand around the corner and frying somebody you can't see physically)?

Do some of his targets have cover if they're got another person standing between him and the mage, thus providing a penalty for some of the people in the area of effect?

If so, how would you figure this in, since the mage only makes one roll?