NEED HELP WITH OUR 5 YEAR OLD SON

My husband has a 5 year old son from a previous marriage.  Due to his mother being "unable" to properly care for him and his sister, my husband has full custody of both of them.

We've been together for a few years and got married in November of 2008.

At our previous residence, which we moved out of in October of 2008, my step son had torn the walls up in his room to where you could see the insulation.  He had torn other things up like the floor and the walls.  When we moved into the new house, which we're renting, we noticed that the behavior had stopped.  The way we got it to stop was I went out and bought the kids nice things for their room, like posters and new bedding.  Thinking if he had new things in his room he would take better care of it.  That was right before we moved into the new house.  

But now the behavior is back.  I have been noticing the past few months he pulled his blinds off his window and bent the strips.  When I asked him why he did that, he just said "they fell".  I told him blinds just don't fall on their own so he ended up telling me the truth.  He got punished for that, grounded to his room for the rest of the day.  He pulled his blinds off a few times after that, even after I keep telling him that the house we're living in doesn't belong to us, that it belongs to other people and they wouldn't appreciate him doing that stuff.  So I just took the blinds out of his room.  I've noticed other things he's doing in his room.  He's peeling the paint off, he unraveled the carpet outside his bedroom door.  Since I didn't catch him doing that stuff I didn't punish him for it, I talked to him about it though.  

Then today, I noticed wood strips in his room and asked him where they came from.  I looked at his door and noticed that a section of the door was missing the wood on it.  He said that they just fell off.  I had him pick up all the wood strips and take them out to his dad.  We reminded him again how important it is to take care of this house because it doesn't belong to us.  He did get a spanking and we made him clean up the wood strips.

I'm frustrated because it's just not destroying the house that's the issue.  He doesn't listen.  When he's told to do something he just looks at you with a blank look on his face.  When he's in trouble and you're yelling at him, he smiles at you almost telling you that he doesn't care.  He wakes up at 5:30a and wakes his sister up who is in bad mood the rest of the day because when she's up too early, she's irritable.  He does this to my daughter too, from a previous marriage who I get every other weekend.  I tell him constantly how he's not the only person in this house and how he needs to have respect for others.  One morning, his sister woke him up early so I yelled at her, even though in my mind I felt she had a right too, but I wanted him to see that no matter what, that behavior is not tolerable.  When his sister asked me why she got in trouble I told her that if I don't punish her for it, he's just going to see that if she could get away with it, then he could.  He's been lying to me lately, a lot.  He runs in the house even though I yell at him constantly for doing so.  He'll get 3 timeouts in 20 minutes for running, because he forgot.

We've had him diagnosed with ADHD and he's currently taking Focalin.  But the school is now saying, for the past few weeks that he's acting worse then what he was before the medication.  So we're making an appointment with the doctor this week.

Is there anything we can do to curb this behavior.  We're both getting frustrated, to the point where my husband and I just don't care anymore.  His behavior may not seem bad but there's so much more I didn't even mention in this.

We just need help and please don't recommend sticker charts because they don't work.  I did those for 6 months and he didn't even earn a sticker.  He was close one day and I was cheering him on, then he decided to do something and I gave him 3 chances and he didn't stop.  He would see his sisters get prizes and then cry and beg because he didn't get one.  It's like he doesn't remember what the punishments are for bad behavior, even when he gets punished for the same thing within 10 minutes.

Thank you!!

(at our wits end)