Best Way to Keep 10% Team Bonuses?

[Regev]

Thanks! I did use search, but found nothing. I even read Al Svalgard (is that his name?) long guides before posting.

So to cover all bonuses I basically need my substitutions to be something like this:

1 GK
2 DCS
1 DMC
3 MC/AMC
1 ST

Questions:

1. But won't the bonus bar go up faster if I train the whole squad?
2. Won't hard drills fill up the bar faster than very easy drills?
3. Will the bonus bar go faster with 3 whistles workouts rather than 1 whistle workouts?
4. Why not train the whole team - since they gain 48% condition a day anyway?
5. If I have an MC/AMC who is 40/50 skill points into becoming a DMC, does he also count as a defender in training?