1. Yes
2. Yes (If I understand what you are saying correctly)
1. I misjudged either my approach angle or target proximity.
2. The target changed direction in an unexpected way and I could not avoid him.
Not to pick on ya Zoney but....

1. It's your fault for midjudging, hence "bad sa", hence an indirect choice.
2. It was only unexpected because you midjudged it. Again, your fault, and an indirect choice.
But seriously most collisions occur when someone tries to pull for a gun solution whilst completing a turn, meanwhile the other guy is trying to do the same thing thinking that he is going to edge out the other fellow and get that gun solution. Next thing you know there is a collision. The fact of the matter is, there is usually enough information at hand well before the airplane you are trying to shoot flies through your window. It stands to reason that a noob will fall victim to this type of collision much more often than a vet who has lots of experience and can foresee it occurring before it does so he changes his vector to avoid it. So there is clearly a strong element of SA involved with avoiding it.