Those are some very good questions, but there are a couple of strange events which makes me think this has something more to do than electricity. Not only did the lights go out but even the things that held a charge went out immediately, like the phones for instance. I would understand that once the power went out, there was no cell service, but if the phone was fully charged, it would still be on for at most, a few hours, but in the pilot, the phones and even the cars went out immediately. This almost leads me to believe that maybe whatever happened, affected more than just the power. So, there must be something more, and those devices we saw is the key to whatever's going on.
"There will always be adventures for another day." - Chloe Sullivan
"Continue to write for as long as you can read." - My Great Grandmother