use the apple hardware test cd that came with your mac
It's going to apss though.. trust me.
similarly, i don't believe there is a white spot issue with the 12"s just the 15"s
sounds like you got a good unit, i second the above recommendation, don't look for problems.. if they are they, they will find you.
i did a dead pixel check on a powerbook i bought a while ago, and found one, right in the middle.. i never would have seen it, after that, i saw it every time i looked at the screen..
ENJOY IT.
and yes, fwiw, i setup a new 12" the other day at work, and the heat issues absolutely seem resolved..didnt' even get warm when i ran xbench on it.