Hi.
On the stim and hitting issues, many years ago, when my kids were young, we purchased a free standing punching bag thing, quite a lot like those huge heavy bags that are in gyms, but it stands on the floor and you fill the a large plastic base with water or sand for stability. It was really great, as it can be punched and kicked and pushed up against with quite a lot of force. Also, you may remember from childhood, those large weighted blow up clowns, that you can punch and stuff. They tip over, but generally do not fall over, and pop back to the upright position. They are not as durable as the punching bags/posts, but they have that responsive action, which can be good, or not, depending on the person and the timing. I think both of these things are really great, much better than beating up pillows, which is what my mother used to have me do, although that is good too, as is pounding and flopping on couches, and matresses on the floor to jump on. All of these things were great for my kids to redirect that energy away from people onto safe objects, and they were also fun!!