Agree on most of your points coach. In addition to your thoughts about training for the Junios/Seniors National Team it would be advisable to set expectations accordingly, meaning either you focus on training your trainee or you focus on winning your division. I doubt many managers let alone anyone can handle both at the same time and it's probably easier for those with established players playing for the Seniors NT. But for managers training 18-19 year-old players IMO the Division III is a much easier platform for them to grow without too much risk of losing games, fans, finances etc. :)