P.F.
The best suggestion I have is to walk away. There is a really good book called Have a New Kid by Friday. In it the underlying theory is that if there is no audience the behaviors stop. My son is older and while we don't have temper tantrums we have anger control issues. I no longer yell and explain. I simply say, I can't communicate with you this way and walk away. It has helped me settle down more and whether his fits continue or not I am not around to feed them. I know it sounds simplistic but it does work.
As for him not wanting to do something, we simply say. The expectation is that you will brush your teeth and walk away. I may say this a few times but always very calm and I don't say anything else until his teeth are brushed. I may walk over and turn the tv off if he has decided to watch tv rather than brush his teeth but the only words out of my mouth are, "the expectation is that you will brush your teeth." Calm and in control are the keys. I know, easier said than done :) Good luck!