1 .y
2. rotation is good to get that players the time, you can use the third match for finetuning if someone is not on 48 min or throw in your reserves
3. 48min is one game (without overtime) most of the season you got 3 games a week so in theory its possible to train 3 players on a position ( i try 2 and the third just a little bit, sometimes its 3, as the coach decides the subs., also stamina and foulproblems is changing the playing time i think, so its hard to get 48 mins corect)
4. as i said before there is numerous influences on the substitutions during the game, but you should at least get 48 mins with 2 players on a position, you can adjust best if you not let the coach decide, but maybe some other people here can give you further information.
5. on the staffpage there is other coach/pr/doctors every week so you have to check there and see if you get someone better.
6.
(381.1)ps: the game is very young and also a bit complex, i dont even know if my answers are corect, but its always good o ask in the forum, many people will help you here.