It's not really an idiot light. The 'Power' light's main function is twofold:
1. Primarily, the Power light tells you when you've triggered the transmission's 'power' shift map. Typically the tranny tries to shift as comfortably and efficiently as possible. But when you want to
go, you tell the car by flooring the throttle. This tells the tranny to use the 'power' shift map, which raises the shift points to near redline.
2. The power light also tells you that there is a problem with the transmission. It does this by blinking 16 times (exactly) when you start the car. Typically it'll light up briefly upon startup and then go out again just to let you know everything's okay.
If the power light comes on any other time (when you turn, when you blip the throttle, etc), it's possible that your alternator is not producing enough juice. When the alternator dies completely, a number of lights on the dash will come on. Why the 'charge' light doesn't just come on, I don't know. But momentary dips in current provided by the alternator can make some lights on the dash flicker. If your belt is slipping (causing that squealing noise) then your alternator may not be producing enough current when it slips, causing some warning lights to flicker on.
Get the belt fixed and then we'll see what happens. I hope this helped. And, by the way, we have a technical forum for questions of a (go figure) technical nature.