Stupid Toddlerhood

I am struggling hardcore with toddlerhood. When my son was a baby, he was so sweet and even natured and adorable and EASY. Now he's become a pain in my you know what. I don't get it. I mean I do, he's a toddler, I get that. But I dont know how to deal with him. Its not even so much temper tantrums, its everything. I am losing it completely.
First there's the eating issues. He wants to eat every twenty minutes and if you dont let him he throws a fit. Sometimes I cave in and give him something, and he throws it on the floor or feeds it to the dogs. At meal times, he constantly wants something (never the thing he points at though)...I give him everything he points to, everything I can think of, and when I run out of things to give him he throws a fit. He wants whats on my plate, even if its the same as whats on his, and if I dont give it to him, he throws a fit. If I do give it to him, he throws it on the floor. That really infuriates me.
Then there's the defiance. Doing things he knows darn good and well he's not suppose to do, things that are not safe, things that he has got hurt doing before (like climbing onto the fireplace). He looks at me and knows he is doing something wrong, but wont stop until I drag him away, then he throws a fit. Going in rooms he's not suppose to and then running away when i tell him to come back out. I have to drag him out by the arm, and now he throws himself on the floor and throws a fit.
I know all this is normal toddler behavior. I read the parenting books, I am doing what I think is right to try and prevent the tantrums. They don't usually last more than ten seconds, but the frequency is the trying part-sometimes they happen practically back to back for hours. The thing I cant get a hold of is my own temper and patience (which I know he inherited, and I know when I lose my cool it sets a bad example), but every once in a while I lose it. I lose my cool and I get so angry. I yell at him-this is what my father always did to me and I swore I never would be like that. I can't seem to control it though. He knows how to push my buttons. So my question is what do you ladies do when you are at boiling point...how do you stay calm? Is anyone doing timeouts yet? I know it's early, but if he knows what he is doing is wrong-which he clearly does, wont he understand why he is in time out?