[tsubaki]

YES to all your questions.
There are too many variables in the theory of electricity to cover, much less on this site.
The chopper alone creates it's own (per say) positive or negetive charge. This is all relative to the given conditions (humidity, etc).
The voltage can (will) jump depending on the applied voltage and whatever may contact it, given the circumstance.
Bad comes to worst, the theory of electricity is just a theory. Whenever someone dies or worst survives from these high wire accidents, it's basically ruled as an act of the gods he lived or died.
spare, your assessment of the insulators being correct for the situation is now negated by the fact of the helicopter added to the picture.
All things being equal till the chopper and the wildman were introduced, the theory is sound, but then it changes.
BTW, the people that own the powerlines write the book on the procedures of maintaince, guidelines and safety, not OSHA, NEC or any other government agencies. So you can bet, this guy is making mega bucks. They did a whole segment on him. Life expectancy?
DID YOU KNOW electricity dosen't actually travel thru wires but travels around them? This is the need for different (or in this case none) insulators of the wire.