pattygirlny -- you sound very overwhelmed! If it is reassuring to you at all, yes, my ds has been through similar phases. I guess you could just try to "wait it out," but it sounds like maybe you want to hear more than that? There are things you could try, if you haven't already.
It sounds like there is a lot of tension between you and your ds, and when things are tense the energy levels can sky-rocket. He may need some "space" from you when he gets angry or mean. If you come right back with a reprimand, a slap, or an order, I can imagine him getting angrier and returning with something worse. And then the situation escalating into a full fledged fight. He sounds like a "fighter!" If it were me, I would try walking away, or at least keeping quiet when he pulled something disrespectful or mean. Then coming back after five minutes or after he has "cooled down" and addressing it in a very quiet, but firm, voice. The message you are sending is "we can deal with this when you are ready to talk reasonably about it."
Also, it might help your ds if he felt a sense of "control" over little things in his life. This has a lot to do with how you phrase things when you need him to obey. For instance -- give choices whenever you can. Ie: Instead of "put on your seat belt we have to go." Next time try "Shall I buckle your seatbelt today, or can you do it yourself?" Then he can choose who will do it, instead of needing to say "no" right off the bat.
About the shopping trips: I wonder if he is old enough for a small allowance? I don't give my kids allowances yet, but mine don't ask for things constantly either. If my older son really seemed to have trouble with understanding the "value of a dollar," then I might give him a certain allowance each week. Then when he wanted something, he could decide if it were really worth it to him or not. And when his money was gone, I could say "Oops. Sorry. Guess you'll have to wait until you have the $$ for it." Allowance or not, consistancy is probably the key here.
These are just ideas that are off the top of my head. Maybe they won't help. But maybe it is worth a try! Please, come here to vent anytime! Sounds like you REALLY have your hands full these days? A great book you could read through (library probably has it) is "Kids, Parents, and Power Struggles." It REALLY helped me deal with my ds better. Your dh might want to read it too.
BTW, what is "ninjutsu?" Is it a martial art? Do you think it helps him to channel his aggression?