on a related note, what level of stamina is required for players?
If I aim to have everyone around the respectable - strong levels will that be good enough, or should I aim higher?
Probably. I accidentally trained 3 weeks of stamina, and got most of my starters up to proficient/prominent, and I'm having a hard time getting them out of the game. They simply don't lose enough energgy during the games to be substituted.