I will add, some thought to your post in the ponts i had an other opion with you:
The way users usually train players is to pick 2 positions.The most obvious pairings are PG/SG and C/PF. This allows you to train at least 4 players
With 2 position training i would train 5 +1 guys, to train only for is a waste of training in my eyes becauseyou could easily share your minutes t 5 guys and maybe give a few minutes a lucky 6th guy.
But i also like 1 position training at start of the career, because you could concentrate on 3 trainees, who could be a it stronger at the beginning(because you only had t buy three of them^^)
A good combination to start out with would be a Level 4 Trainer, Level 2 Doctor, and Level 3 PR Manager. But if you can afford better staff then by all means get them.
I would say staff above level 5 is a bit of wasted money, but this has a bit time for him ;) I would start just with the level 4 trainer, and keep for the first weeks the level 1 doc and PR(the level one doc, i would hold a while)
You should only expand your arena when you are consistently selling out home games.And even then you should increase ticket prices first
you could build some VIP lounges at the beginning(1 or 2), ok but with zero VIP lounges they are automatically sold out^^