You are doing well. Here are some more thoughts.
Nonsense, I know bodybuilders that have been training since they were 12 and are extremely ripped now.
With proper guidance he really doesn't have to worry about when he should start pushing his body hard.
I wouldn't advice doing a lot of back isolation exercises at your age though, but your gym coaches can probably give you more advice on that subject.
You can train as hard as you want. In town here there is a girl who benches 250, squats 400, and deads 450. She is only 15.
Yes Find the proper guidance.
Make sure that your ARE training back like crazy. A good motto is, "When in doubt, Train more back."
Had a chance to talk to my doctor about it back then and he told me about all kinds of problems I could cause; messing up growth plates and the normal puberty cycle with hormones and all that.
1. Doctors don't know anything about training.
2. You will not close your growth plates.
3. The only thing that will happen with hormones is that you could produce more than you would without training. That is always good. The Puberty age is a great time to start training and potentially increase you natural test, and Gh levels.
Also,
It is pretty hard to overtrain when you are in your mid teens. The most important thing is making sure that you find someone to watch you train, make sure that you form is good. Your best bet is to find good training partners, and a good coach / mentor type person. This will help you make more gains than anything else right now.
A good rule of thumb on form is, "No matter what, your form is not good enough and needs to improve."
and
"The people you train with should be correcting / commenting on form every set. You should do the same for them." or "Technique needs constant reminders."
Hope this helps.
