Yes look up nurture vs. nature, but also remember that it's not always that way you have a big say on the inside world. (I am assuming you are saying the inside world is you)
I believe it does, yes. We are the light of the world a city built on a hill cannot be hidden, it is what inspires what we all see in the world. If you want to change the world change yourself.
Yes its true :-/ keep your inside world pretty happy the outside world change like that automatically