[sfem]

They aren't simple questions. There are no definitive answers to them. And there are threads already posted that address these as much as our little group can. Perhaps you might want to join one or more of those threads for more traction than tossing them onto the end of this thread.
In the interests of not being obtuse, my answers to your questions in summary would be:

It is uncertain.
Maybe.
Unknown, but debated from time to time.

For more detail please refer to existing threads on these questions.