Draft has just been so this decision is for way later. The strategy depends on what place you'll be picking from.
The guy won't become very good but probably good enough to contribute to a team at your level as a backup . Generally people would probably advise you to at least buy an all star trainee. There is some fun in training someone from your original team or draft so I'd say train him as a 2nd or 3rd trainee while you look for other trainees. Get a trainee with a bit higher potential next to him but don't overspend. You are just learning the game and also learning how training works. Once you get a hang of everything you'll probably know enough to decide for yourself on whether you want to continue training this guy, sell him, or use him as a backup teammember but look for another trainee. (I don't know what level players are in div V but I'm guessing a guy like this can be a backup at least......is that correct USA people?)
Scrimmage minutes help with training just as much as regular minutes. This is good for training people that are not good enough for your competitive matches yet or for training out of position.
height affects quite a few factors. small players train faster in JR, OD, HN, DR from the top of my head. PS and JS height doesn't matter that much. And IS, ID, SB, RB longer players train better (might be off on 1 or 2 skills but close enough for a first idea. There is a nice training site that has all the data http://training.bb-usa.net/club/home.php)
Yeah forum search is not so great

Crunchy! If you eat fast enough