The problem I have with this concept is that I have no control over the quality of the answers received. If I get scrappy answers or illiterate answers, these will drag down the quality of my subdomain. Well, I can delete the question, I suppose in order to get rid of the unwanted answers, but that is a drastic solution. I certainly would not wish to draw attention to those answers.
Secondly, if I am writing a hub on a topic, I already have knowledge about it, so I do not see the point of asking questions related to those issues.
If I ask questions to which I genuinely want to get answers, it means I do not have sufficient knowledge to write a good hub about that subject area. Thus I will not have any related hubs on which to feature those questions, even if I do receive brilliant answers.
So I'm a bit puzzled as to how to use this question business to greatest advantage.