Basic questions:

Wait, how do you use the editor to change the texture of individual faces instead of a whole brush?

And, when I switch from camera to render by checking off 'render' I only see blackness instead of real-time lighting. The level works fine in-game, though, but I want my real-time lighting! :p

The help I've gotten so far though is appreciated. :)

1) CTRL + SHIFT + left click on face
2) Use F7 to update the render view.