Looks like your second question has been answered plenty of times, so i'll give another perspective on your first one:
I want to be an engineer because I love physics. I love not only to know how things work, but also how to build them. I think of new ideas all the time and am an inventor at heart. It kind of annoys me that I use so many things I don't fully understand, like television, radio, remote controls, etc. and I want to learn how they work and eventually be able to build them.
All that said, you'll know if you want to be an engineering by taking a tour through a Boeing or Lockheed-Martin plant. Just seeing people casually build $80+ million aircraft for a day job puts the coolness of engineering above everything else for me.