How can I be a Chemical Engineer or a Neurosurgeon?

Hi! Im a 16 year old teen and am planning for my future. I have 2 dream careers that are making me confuse to which one is really suitable for me. Im currently in Science stream. What course do I have to take to achieve that career? What subjects do I have to master in? How much is the salaries? What will I work on/do if say I got the one of the jobs? How many years do I have to study catch one of those careees? I hope anyone can explain this to me CLEARLY as I dont want to make the wrong decision and end up badly. As they say, "Career planning is life planning". Thank you!