Wow - God bless you for adopting this child. I was just listening to Focus on the Family radio program this morning and this grown man was talking about his childhood and teen years as an "orphan". I cried listening to his story. What a blessing for this child to have you as his parents. First I suggest you go to Focus on the Family's website - they are a Christian organization - but even if that's not your world view they have good information - you can always listen "around" the information you don't want. Their website is family.org - just hearing this guy's story might be very helpful for you. I think you can download the podcast or find another radio station that will be playing today's program in your area this afternoon.
Basically this man said that boys in general, and foster kids specifically have lots of anger. I have an 11 year old bio son and he's got this anger sometimes that just seems to come out of nowhere. I think it's all the testosterone - for which they have no outlet. Hundreds of years ago they would be learning how to protect their village and hunt to provide for their families - now they sit in school for hours...
Once the anger has begun it's like a wave on the beach - it can't be stopped. You have to address it when you're in the calm moments. Tell him how you chose him - that you wanted him and planned for him - and you are never going to dump him. I think that's a genuine fear for kids like your son. Kids have to be told, retold and then reminded again of things. So telling him once or 20 times won't do it - you have to tell him ALL the time. Tell him we love you, we're not going anywhere, we are all going to work through this - and even when you're mad at the world and feel like you hate everything we still love you - even when we're really tired & frustrated, we still love you and are not going to let go of you - ever.
Now lay down the boundaries. Kids need to know that boundaries exist in order to feel secure and loved. My 14 yr old will kick and fight against her boundaries - but when I pushed her for an answer she finaly admitted that she was glad we were "so overly protective - deep deep deep down inside". They don't want to admit it but they're secure with rules and limits. Tell him that the limits and boundaries are for his protection and that if you didn't love him you wouldn't have the limits on him. Tell him that if he doesn't listen and follow the limits that you've set then he's outside the circle of protection. Like a llitte kids who doesn't hold your hand, or pulls free of your hand when crossing the street - you can't protect the child who runs out into traffic - but you can protect the one who holds your hand. Explain that you don't need him to physically hold your hand, but figuratively he need to hold your hand so you can keep him safe. That's your job as his parents.
As for chores, your job as a parent is to teach im and show h im how to handle the stuff of life for when he becomes an adult. Taking out the garbage or loading the dishwasher are things he needs to know one day to be a good husband / dad himself - and the way to learn them is gradually at home. Tell him the place to learn life lessons is at home surrounded by people who love you - not when you get to be an adult surrougnede by people who don't neccessarily love or care about you. How much better to make mistakes when there's loving people around to help you get back up!
Set up expectations - the concept of the self-fulfilling prophecy. Tell him that while you know self-control at certain times isn't always easy - he's had to do alot of things in his young life that haven't been easy and you know he can be successful at this. Help him come up with ways to help himself gain control - have you been to a good counselor together? From a Christian persepctive I find that praying helps my kids gain control in moments when they feel that they might spin out of control - and self-control is a fruit of the spirit - but that may not be an approach your family is comfortable with. Talk to counselors about ways to help him gain or regain control.
Be sure to praise him when he does handle things well. When you see him getting angry then controlling himself make sure he knows how proud you are of his ability to work at it. It won't be perfect, there will be starts and stops, but remind him when he's struggling that you know he can do this and you have great expectations for him.
When he does lose control and and goes into a tailspin you need to find a way to calmly remind him doing by doing what you've already been doing - we love you we will always love you but we won't address this now, when you've calmed down we will. he's only been on the planet 11 years - he's got so much to learn and unlearn. He's learned that people who he should be able to rely on can't always be trusted and relied on - and he's got to unlearn that. YIKES!!!
Finally maybe you should write a letter to him that he can refer back to when he's going through those dark moments. Make a few copies knowing that he may tear up the first one or two in a fit of anger - won't he be surprised when you give him another copy. Tell him how you know he was planned to be with you since before time, that you were meant to be his parents and you love him and will never leave him or desert him. Remind him that he's precious and he's loved. If you're a Christian or a Jew you can find beatiful verses in the bible that will affirm that. I like Jeremiah 29:11 - "I know the plans I have for you declares the Lord, plans to prosper you and not to harm you, plans to give you a hope and a future". Psalm 139 is another passage that affirms God's presence in our lives. Tell him the things about him that make him special - his sense of humor, or the way he roots for the udnerdog, his great math skills, or his tender heart for kids, etc.
And pray - seek God's vision for this child. Ask for discernment and guidance. I truly believe that God cares about the details of our lives and wants to be involved in working these things out.
And give yourself some slack - parenting is a tough and thankless job for many many years. You are probably doing better than you realize and your son may even tell you that. When he's in a calm mood - ask him "how do you think this is all going? How are we doing?" You may be really surpised at his response. ;o) God Bless!