Sounds a lot like my daily life with my 2-year-old!
In your post - you say you ask him to do something, when he says NO, you just "give a look of disappointment" and walk away. I am thinking, perhaps it would be better to focus on the follow through at that point. Meaning, you said it was time to come to the table, so he must come to the table. Or, he can go to time out. That is the choice! It is his decision. You are the boss.
I give my daughter 2-4 choices of food each meal, at least one or two things I know she likes, and if she eats it, great . . .and if she doesn't, well, she doesn't get to eat. It is up to her. She also has to sit down at the table to eat. This may be wimping out . . .but sometimes I just join her at her little table and we just eat there together. It is easier. (My husband is not usually home for dinner.)
For toy clean up, I will say, now it's time to clean up our toys! Can you sing the clean up song? And then we clean up together. (This works most of the time but not all of the time.) I think maybe at 2 they're a little young to do it by themselves without getting distracted.
Also if she is rude to me, or hits me or something, I tell her what she did wrong, ask her to say sorry, and if she doesn't, she goes to time out (for 2-3 minutes). No exceptions. I try my best not to yell at her. Just send her to time out (and speak in a firm voice).
A good piece of advice I read somewhere that really works with my daughter: Whenever you need your toddler to change activities or do something, give them a 5-minute heads up. Such as, OK silly pants, we are going to change your diaper in a couple of minutes. Then . . in a few minutes, I say, it's almost diaper changing time! And then a few minutes later, I say, OK, it's time to change your diaper, let's go in your room together!
This advice seems to work with many things. ("We are going to eat dinner in a few minutes!" "It is almost time for bed!" "We are going to the store soon!" Etc.)
This may sound kind of silly but I find that watching "Supernanny" is extremely helpful and I've learned some things that work.
Kids are all very different - I have no idea if these things will work with your son, but hopefully it will give you some ideas. Good luck!