b) The assurance of getting paid is a potential problem, I dont think 
  theres any way of giving that assurance...

Of course there is. It's called escrow. I pony up the money when I ask the question. You pay it to the answerer that I designate the winner. If I don't designate a winner, you pay the money to a random answerer, to keep me from never picking a winner, but benefitting from their answers. Finally, of course, if nobody answers, the money stays in the account to use for the next question.