Your arena is fine. The max attendance for a game is 22 to 23k. So ideally arenas that I have found are 15k bleachers 5k lower tier, 500 courtside, and 50 luxury boxes. From here people decide whether to build more courtside or bleachers. I'm going to build more bleachers next and then I'm done. My arena will be 15,500, 5,550, 500, and 50 for a total of 21,600.
For my 6 trainees here's what I did.
Age 18: 1v1 Forwards all season
Sold my three worst trainees at the end of the season/kept the 3 trainees that were similar height. Based on height decided small forwards were the ideal build
Age 19:
Weeks 1,8, & 14 JS G (only 2 two games those weeks)
Weeks 2-7, 9-10 ID
Weeks 11-13 IS
Age 20:
Weeks 1,8, & 14 JS G (only 2 two games those weeks)
Weeks 2-7, 9-10 OD
Weeks 11-13 JR
Age 21:
Weeks 1 & 8 JS G (only 2 two games those weeks)
Weeks 2-5 JR
Weeks 6-7, 9-11 PA
Pretty much after doing 1v1 F. Their driving/handling was at lvl 11 or 12. I just trained ID, IS, & OD until it equaled DR & HD. Then trained JR and PA until it equaled JS.
Here is what I used;
Trainer: lvl 5
Youth trainer: lvl 6
Gym: lvl 3 (not until all-star week of this season)
Gabriele went from 62 tsp to 106, bought for $20,000 sold for $1,285,250 (Thanks!)
Stefanoni went from 58 tsp to 101 bought for $3,000 sold for $813,000
Heredia went from 57 tsp to 103 bought for $51,000 sold for $1,610,200
The reason why I think they went for more than I thought is because they were all really balanced and their salary was super low for their tsp leaving a lot of room to still train them. I'll be interested to see what their salary is for next season. I wouldn't be surprised if Gabriele gets to 120+ tsp before capping for an allstar potential player.