1. Managing a NT gives me reputation to get a job at a better club, but that's down the line after I leave (or am sacked by) the NT. Not sure if you can get a club job while running a NT, it never happened with me (the oppositive, though, is true: you often get NT invitations while running a club job).
2. I don't think so.
3. Sorry, I don't understand your sentence. Any win counts (nice results, improbable wins, etc.), even if you don't win silverplate.
4. Each nation is different, but it's often the case that all team A slots are taken. If so, I remove one player from team A, and then select a player from U23.