Thanks Steve. That helps a lot. You made me thing of another quick question…..
Suppose there were bumps or even corners of the wall that I wanted things to be writing onto. Should I make the actual file in photoshop and have these corners or bumps already applied and then animate them. Or should I just make them flat and apply the bumps, corners, shading, etc. in AE?
In that video I posted the link to, they tackled that probelm rather successfully on a few small bumps, etc.