As far as Japanese martial arts goes, I would avoid anything that ends with "do" which means "the way of" and rather choose the "jutsu" variation which means "the art of".
The difference is that jutsu martial arts are more genuine and closer to their true martial (war) origins while the "do" versions are more adapted to competition thus they left out lethal techniques in favor of sports.
I'd agree but the problem is teaching 'jutsu' techniques to children who
may not have the self-control and discrimination not to apply them to class-mates. We are talking about 5-year olds here. By all means introduce the heavier stuff later. As for grappling , that tends to favor the weightier of us. I'd look at aiki-jitsu or hapkido for leveraging techniques.