making sense of overclocking/undervolting

Here are my thoughts; correct me if I'm wrong.

There are 3 variables to overclocking/undervolting:
1. Clock speed
2. Voltage
3. Heat (independent)

Statement 1: Voltage is the only thing that produces inefficiency.
(If this were true, then there would be no point to my 6.0x CPU multiplier, because both it and the 7.0x multiplier are stable at .875V.)

Statement 2: High clock speed, voltage, and heat give pain to the CPU over time and could one day result in it self-destructing.

Series of Questions: Are the volts of the 9800M core, memory, and shader locked, or do they increase as you overclock? If they are locked, and if you are able to keep the GPU cool, then is the barrier to overclocking more based on the locked voltage? Is the GPU like a CPU in that there is no damage to the hardware when you clock into the realm of instability? Is the memory's barrier heat or voltage?

About my CPU, does the SuperLFM, which cuts the FSB in half, produce less heat than the standard 6.0x multiplier, if both have the same volts?