> 7. I'm not yet convinced that there's a huge market for paid responses when the Stack Exchange network and Quora both offer large userbases who give their time to answer questions for free.

Perhaps it is this model they are trying to defeat. If an answerer has the opportunity to earn real money for their time, it might be theorized that they would opt for that over the karma systems. It makes sense for a greater breadth of expertise, as respect loses its inherent value as you grow beyond the social circles or occupational circles.