Jaibird,
Re towing to runway.
I remember one of the reasons it was put to bed was that it caused big delays.The taxing speed was low and caused big queues of planes and delays.
I would imagine the pilots then have to start up on the runway and do their checks there causing some more delays.
They are trialing electric motors on planes for a while now,however problem up to now has been increased weight and strain on undercarriage.
Sure this will be the way forward in the future though.
Nigel