[yndy]

Short passes trains passing ability.

The primary skill of playmakers is playmaking ability and that is what you should train.

With your weak coach and 3 assistants I would say training would take 11-13 weeks for playmaking skill. I strongly suggest you buy a passable coach with poor leadership (assuming you can't afford a solid coach with poor leadership).

Playmaking training increases the playmaking skill of inner midfields (100%) and of wingers (50%) so by playing a league game and a friendly one each week with 3 inner midfields and 2 wingers each time you can train 10 players in playmaking per week (6 at 100%, 4 at 50% meaning it will take twice as long for them to grow).

No you cannot see progress every week in skill but you will see the assessed value increase. You can use a manager program to help you monitor your players (I use HT Buddy) or you can make a note when they increase every time.

Yes you can change training whenever you feel like it without loosing any training.