I use open source software, and I am interested in becoming a contributor, but at present I am not. I think the best expert level questions will come from people who have regular experience at working on open source software (not just using it). People who have seen what problems need to be addressed.
Do we have a large proportion of such people? If not can we invite more? There is an invite button for sending email invitations to individuals during private beta (although we can't advertise publicly until public beta).