It sounds like this young lad is having a ball! He has found out how to make his world work the way he wants to, and is exploiting it to the full, and who can blame him! I think you hit the nail on the head when you said he is too clever by half.
This might sound very drastic, but I think you need to throw out any old tactics, he knows what you are doing, and hes not going to buy into any of your strategies, because he will only behave on his terms, you have seen this with the selective memory.
If I were in that situation, I would make each and every privelege something to be earned, not an automatic right. I would use a points or coins system, eg, clean your room, 5 points. Earn 50 points in a day, yes you can use the playstation/go to a friends house/watch a movie. Otherwise, no, no, no. It might sound harsh, but its kinder than allowing him to think that life is that easy all the time; that when he leaves home and grows up, he wont be able to work people over as easily.
You could make him earn wages this way, but I couldnt, my budget wont stretch anymore!
Good luck, some of our other posters might have some other ideas for you. All in all, he sounds like an insuppressable confident free spirit, he will probably grow up great.
