I have worked with children who share some of the same disadvantages that Danny does. Some were severly violent, some were not. I understand the workers wariness of working with someone at such a disadvantage but there has to be someone who can just simply give you a hand. In my town, we have a company who works with disadvantaged children, their diagnosis range from autism to ADD to any behavioral problem that can be documented. They also work with and house girls with behavioral issues.
What you first need to do is document what he does on a daily basis. The good, the bad, the trivial....
Keep him on a constant schedule, which you may have already figured out....
And research some different companies that you like that would be of assistance to you. Even if they aren't in your area, still talk to them. They can more than likely refer you to a company closer to you.
It sounds like you have a fairly good handle on things but you could always use extra help even if it's just a couple hours a week. They can teach you tools to use with him and different methods of getting across to him and hopefully, in time, he won't be aggressive or he'll have learned ways to deal with his aggression so that he doesn't lash out at you.