I've just finished reading this thread, oh my what an awful situation!
I'll indulge in a bit of quackery (not quacking) and say he sounds like an NPD with ADHD or Aspergers thrown in. With regards to treatment for alcoholism, I know it's a case of "you can lead a horse to water, but you can't make it drink", in other words dragging them kicking and screaming to rehab won't do much unless they WANT to get better themselves. Much the same may be true of NPD I fear, but the hope is he can get help with his ADHD/Aspergers and become more independent.
If you lived in the UK I'd probably tell you to go to Social Services, explain that you're being terrorised by your adult son who punches holes in doors etc. and hopefully they'd move him out of there to a council flat of his own or some kind of facility. At least, that's what would have happened 5 years ago, but thanks to the current government's ideological obsession with forcing everyone into work, I'm not convinced it would still happen.
Welfare state in the United Kingdom - Wikipedia, the free encyclopedia