To Revo:
Guards I'd go with #2.
Guard 1: Probably never make the team, OD is terrible, along with that passing. He'd be a pure shooter/ballhog, and I don't think we'd ever need him.
Guard 2: A solid player, would be one of our better defenders, and useable in any offense.
Bigman one is a bit tougher, but would choose #1 in nearly all situations.
Bigman 1: Likely reserve type player, solid at everything, but not great at any one thing to exploit opponents.
Bigman 2: Despite also having bad defenses unlike Guard 1 he might make the team if I felt we'd be primarily inside oriented because he can score and rebound(kinda).
Question #2:
Well first I'm going to wait to set my limits until after I've seen all our players. As for if I'd add a player if they didn't meet a minimum, well maybe. If they excelled in some other area it is possible. There would be skills I'd be more flexible with(example it'd be easier to make the team with bad JS and great OD/PA than to make the team with bad OD and great JS/PA). On things like OD/ID/PA I probably would set hard caps for certain positions, but they wouldn't be too extreme at first. Also I'd always try to take the age of the player into consideration, if he's old and capped then he'd probably not make the team, but if he's young and training he'd have a much better shot despite not meeting the requirements.
To Mzungu:
Yep I believe having mostly more balanced players is the way forward for England. Many of the top NTs monsters would just be unsustainable and we need to be able to count on all of our great players since we can't churn them out at as high of rate as say an Italy. Though as Vendabal said it's still nice to have some specialists for certain tactics, in the ideal world I'd think these would be our bit lower potential guys who probably wouldn't make the team without it.
As for getting guys to train out of position, well it's tough, I've found the best method is usually to be honest with them that it will probably hurt their team in the short run, if you don't do that than you run the risk of losing them as a trainer in the future. Recently I've been trying to get managers with high potential players (mvp+) to start their training with secondaries to avoid that salary problem. So basically all if they agree or not, no way to force them to it.
As for the U21 vs NT training, I usually advice completely based on NT potential until most likely midway through their 20 year old season. Then if it looks like they are going to be the leader of the U21 squad next season, or fill a role that no other prospect can I'll let Srez handle them until the end of their 21 year old season(I still check in every once in awhile). But if it looks like they are going to be a backup/non essential player then I continue advising completely based on the NT. An example of this would be Gregor Simpson from last season, he kind of popped up on me at the beginning of his 20 year old season, and it was immediately obvious he'd be an U21 star if he trained that route, with a lack of great big men this last season I agreed he shoulld be trained to help the U21's until they were out of the tournament, as soon as we were out of the tournament he switched to passing training and got in very nice 2 pops since then.
To everyone: I'll be moving over the next couple of days, so I'm not sure how available I'll be for the next week or so, but I'll try my best to continue to answer questions.