> Does LADWP "charge" LAMTA for electricity for the subway/light rail lines?

I see no reason why not. Hetch Hetchy charges Muni for the power (it isn't free, though compared to PG&E rates it's nearly so). SMUD bills RT for power (also much less expensive than PG&E). LADWP probably has a similar deal available to Metro, at least for the portions of their lines that are within the City of LA.

Does VTA get Hetch Hetchy power or do they have to buy it from PG&E? If the latter, it could be another reason for poor service (besides bad design). Will Caltrain get Hetch Hetchy power? If not, PG&E will eventually bankrupt them. Hetch Hetchy power can be sold to public agencies; they're just not supposed to sell it to PG&E (yes, I know, there's the Newark-SF wheeling deal, that is often questioned).