I'll start by suggesting that a lvl 6 trainer is worthless for this guy. After level 4, the value per dollar spent weekly greatly declines. There is a bit of a debate as to whether or not a lvl2 thru lvl4 trainer is the most worth it, but it mostly depends on how fast you want this guy to get close to his potential.
Additionally, i'll point out that while salary efficiency and other things are quite important, no one area gets it's potential realized if you cant manage game shape. So i would learn to keep guys to within a 48-72 minute per week gameplan.
As to what you should do. The 2nd guy is less than what you can find on the transfer list for under 20-25k in cost. So if you want a 2nd guy to go with this trainee, best to go out and take care of that and junk the other one (TL him). I would make a decision now as to whether or not you want this guy as a PG, or as a SG, or perhaps as a SG/SF hybrid type player. I think the best choice personally right now is the 2nd option (SG), which means ID will get trained some.
IF you want my personal opinion:Train ID until 5. (Inside Defense @ C)
Train PA until 5. (Passing @ PG)
Train DR until 5. (OnevOne)
This gets him to at least a level where he does not necessarily hurt your team as much in the games he plays.
Train ID until 8 (Inside Defense @ C).
Train IS until 9 (Inside Scoring @ C).
This will get all of his inside skills out of the way earlier.
Train OD until 10 (Pressure @ PG)
Train DR until 10 (OnevOne)
Train Passing until 10
From here on, you can choose to bump up JS to whichever level you feel is necessary, you'll want to put more into other areas (OD), it's really up to you at that point.
This is not going to make him train the fastest or most efficient, but it will help you improve your team performance, it will make him more well rounded and salary efficient, and will get you to the point where you have a good understanding of what you need to have in your division against your competition.