>>1 A lot of people are still unsure what they want to do with their lives at your age. I thought I knew, then halfway through my university degree I discover it's not what I want (the irony).
Try a diversity of courses -- chem, bio, math, art, music, history, political science, etc. and see if something catches your interest. When you get to university or college, you can start with a general, nonspecific program, to test the waters (a lot of people do that in their first year and a half) before deciding on something.
Polytechnic schools have interesting programs, have a look at those, usually it's more hands-on and more interesting than what college/university has to offer.
I'd suggest, after you graduate high school and if you still don't know what you would like to do, to go to college/university or a polytechnic school and enroll in a program that will allow you to find a job you can make a living out of after you graduate. Start with that, and as you progress through your degree (especially that first year), try different courses (those electives you need to take? Good way to test the waters).
Hope that's some use to you. Don't stress out too much about it, you'll definitely find something that will make you think "That's it! This is what I wanna do for the rest of my life!" In time, in time :)