A couple questions of legalities

[GT40FIED]

Alright...so I just got back into town (at school) yesterday. A few blocks from my house I was looking forward to getting home after an unusually long drive (a head on accident shut down the highway and forced me to take a shitload of backroads to get around it). I was driving down a 4 lane street (2 lanes either way) when I look ahead and see some asshole riding his bicycle towards me in my lane...against traffic and in the middle of a lane. Now...generally I hate it when people ride bikes in the street unless there's no sidewalk...but blatantly disobeying traffic laws is something different altogether. So my question is if I would have hit him, am I criminally at fault? Since people on bicycles are supposed to follow the same rules of the road as cars, I figure hitting him would have been kosher. I mean...if a car had been driving directly at me going the wrong way and it hit me, there's no way I'd be at fault. I contemplated hitting him purely out of spite, but instead I got a few hunder yards from him and gunned the engine until I was about 75 feet away and changed lanes. I know...I'm an asshole...but I figure he had it coming.

Secondly I was curious about justifiable homicide (self defense in particular). Say I find out someone is coming to kill me and I have time to get ready. If I lay in wait with a weapon and kill this person before they have a chance to kill me, is it still self defense or is it premeditated? I mean...premeditation involves thought and planning...something I would certainly have to do to defend myself. Plus if I'm holding a gun and so is the other person it stands to reason that we're equally dangerous to each other. So...thoughts?