Do you ever take it upon yourself to confront those who you think aren't good drivers?

That's a very dangerous mindset to have; things can escalate and get out of hand rather quickly; saw it many times in my 54 years of driving i.e. here in Florida lots of folks carry weapons in their vehicles and/or have a concealed carry permit. Just drive defensively; it's the best you can do.

Is flipping someone off considered a confrontation?
If so...yes. Frequently.

Slows down n let's em pass.

Oh yes. My mother tells me I'm going to kill the children then constantly get yell at me and grab the wheel. I don't know how I'm soposed to get my license this way.

yep... I punch them in the face... plenty of tossers on the road...

Rarely, and only if I know them well enough.

Not worth

No. Around here bad drivers are often excellent marksmen.