I think your last post was very informative. It is obviously a challenge for your son to have moved from one place to another and we're talking big move.
I think the solution is a whole lot of communication, you've probably heard that before but I have seen a lot of parents talking to their kids instead of communicating to them, I mean a 2 way communication, where you both exchange ideas, this would be a start.
Make a list of rules, the dos and donts of the the house and ensure they are fair.
Sit down with your hubby and child and go other these rules and get his agreement that he'll follow them and both you and your hubby have to agree you'll follow them too.
From that point on do not be reasonable if any rules are broken, do not be harsh at first but always tell him what the consequences will be.
Personaly I am agaisnt corporal punishment but if it has to come to that for you, I would advice never to be angry when you slap your child, never to the face, preferably the back of the hand, never in the purpose to inflict pain, and never in an angry way and not by surprise.
Be patient (which I think you are) and believe in your child do not give up on him. It will work out.
I have a 7 year old and we are having a great time...90% of the time