Okay, to get more in depth on the Kanohi transferring power to the wearer:
The purpose of the mask (besides it's actual mask power) would be to act as an amplifier/gatherer for any source of power, like magnetic, heat, solar, static electricity, radiation, ambient light. The mask would work almost like a lightning rod. For this to work, we have to assume that the type of protodermis from which it was made is highly sensitive to a change in any of the sources mentioned above.
Basically, when surrounded by energy, the mask gathers it (sorta like a satellite dish or solar panel strapped to your face) and transfers it to the wearer's head. I think that those clear head-stalks are where the energy is stored/processed. (battery) Some of the energy goes to maintain the lungs/other organs, and the rest of it is used to power the articulation of their limbs. I feel like most of it would have to be saved tough, because when they want to use their elemental power or mask power, that probably takes a lot of energy to maintain.
When using their mask/elemental powers, the energy probably goes back through the mask, but instead of being like a solar panel, the mask acts like a big transformer. This would let it use up less of it's stored energy while still giving a lot of power for whatever the Toa needs to do. It also explains why the Nuva masks are better than the regular masks, they simply are better at gathering/converting/releasing energy.