No, thats not true. It has large number of professionals of art & design too. I have seen some very fine pencil art & paintings there....for art age is no limit,so as deviant art...it has people from all ages..i would recommend you to start from there, as you'll get feedback from people with some knowledge & education about art....not just art lovers!
I can't comment on this. BTW Militaryphotos .net has good forum to share your stuff. Deviant art is another good platform...both has large number of audience too!