Thanks for covering all bases here mate.

I like what James Altucher has to say:

"...for my friends who write non-fiction books: I've seen people write best sellers to non-sellers, but the ONLY way that I've seen serious money being made by authors that I know (even for bestsellers) is by either doing speaking tours after the book comes out (far exceeding whatever they got in advances) or by selling information products that complement the value they deliver in their books."