I wouldn't say 90/10 lol, but in theory you are correct, something more meatheads need to realise..I've had 9 months experience weight lifting now, and it's all nutrition and form/technique.
Ensure your concentrating on your movements rather than impressing people how much weight you can actually lift. As for diet, weight lifting is 90% diet, 10% effort in the gym - anyone with experience will tell you that. Improve your diet, and improve your workout routine and the results will show.
This is true. Complete and utter myth that it stunts growth (however at a young age <15 it CAN compress the spine but only through heavy deadlifting etc). You know what stunts growth? Not eating correctly.given your growth plates are closed when you start lifting, it probably wouldn't do anything
having said that, lifting heavy at a young age (doing squats etc) probably decompresses your spine moreso and could maybe stunt your growth