as for age group how young would you start them? 16? you'd need players in there 20's as well or even older, kinda like what the a-league has done. is the player talent pool that big and would this help? not sure there may need to be other systems in place to make sure these guys will better off in this team than a club side.
It would have to be under 21's or similar to have a chance of having a good go at it