I have a common snapping turtle that is 1.5 years old and weighs 4 and so lbs.

1.) Does this sound normal and healthy as a growth rate? (had another before that didnt grow this big this quick.)
2.) Will it keep up this growth rate, or will it slow down?
3.) How large have some of you guys gotten their common snappers?
4.) Do they seem to lose their tameness with age? (Mine right now won't even hiss no matter what I do to it.)
5.) Can you sex them, and if so, how?
6.) What other food choices do I have to feed him? (I use reptomin, minnows, goldfish, chicken, worms, crayfish, etc.)

Thanks, Chris