I really disagree with the moms who wrote that there is nothing wrong with giving him a swat on the hand just because they are too little to reason with. It teaches him that big people don't have to care about little people's feelings. It will definitely get his attention but not in the way you are looking for.
First of all, your son is doing what one of my girlfriend calls "gravity experiments." It is totally age appropriate and very frustrating. He is seeing what happens when he throws things. It is very exciting to him, both to see the crash and to see your reaction.
From what you said, he doesn't do it until he is finished eating. It sounds like it is his way of saying, "Get me out of this chair. I'm bored." To stop this behavior, take him out of the high chair before he starts doing it. Watch him when he stops eating and ask if he is finished. If he doesn't start eating again, take him out of the chair. Once he is out of the chair, praise him very loudly and happily when he hasn't thrown any food (even if it is just that he didn't get the chance).
At this age, he can't understand time outs or other punishments. But he does understand that getting attention from Mommy and Daddy is great, especially when you are happy with him. You just have to avoid the opportunity to misbehave. I think you had the right idea when you didn't show emotion in response to bad behavior.
In other situations, if he is doing something you don't like (drawing on the walls, banging on the furniture with his toy hammer, hitting the dog with a toy....), tell him once not to do it and tell him that if he does it again you are taking it away. When he does it again, take it away immediately and say very seriously, "I'm sorry you're upset, but you aren't allowed to (whatever you told him not to do). You'll have to find something else to do." And go back to whatever you were doing.
Also, as you are finding out, boys and girls are just different. My father told me this recently: I was the oldest and when my dad remarried and got a stepson, all his experience was with girls. He thought his stepson was mentally ill. He would run and jump and destroy things. All I ever did was play with dolls and color. Boys are just different.