I don't think karma is reality. I am kind to people only because it makes me feel good & because cooperation is more productive in general than not. Evolution did that.
Probably not, the placebo effect is real though. Sometimes just anticipating that you're going to be happier because you made others happy can make it so
Plus, if you're able to impress this idea on someone else, they might try to make you happier for the same reasons. Kind of a self-fulfilling method of bettering the world
I have plenty of evidence to suggest that karma is REAL. I may link to it in the future. Keep in mind, karma is equated to a wheel that keeps spinning.