Well, there are several ways to become a pilot.
1) Go straight to a flying school and build up your hours after high school.
Advantage: Get hours really quick while you are young
Drawback: Airlines normally require you to have a bachelors degree or better aside from hours gained. Hard time getting in an airline.
2) One option would be to take up flying as your undergrad course( Civil Aviation, etc)
Advantage: Build up your hours as you take up your degree. You can go straight into an airline right after you achieve you hour requirement(from 500-1500 hrs)
Disadvantage: God forbid you fail in medical exams or have an incident and lose your license, you have no fall back job. This can happen and does happen.
3) Finish college(any course other than aviation) then fly in an aviation school.
Advantage: You have a fall back in case something goes wrong.
Disadvantage: Takes more time and money(this depends on the school though)
Mechanical Engineering could help augment your knowledge in aviation but is not really a requirement. As long as you have a good 4 year course from a good school, that would be enough. (Hard work and perseverance with the proper attitude is key
)
I'm not really sure with PALav's policy but I think if you have an impacted tooth, it might have to be removed. Anyway, they give you a dental examination during the selection period and they will tell you what needs to be done with your teeth (extraction, cleaning, etc). As long as your speech is good then there is not much to worry about. Learn and speak good english! I can't emphasize that enough! That can give you a good advantage especially during the interview.
All in all. There are so many ways to be a pilot. Look at all of them. Don't just jump right away. I have some friends who are pilots yet who don't have jobs because they lack certain requirements. I myself almost got lost if I did not research well enough. Thanks to some friends who gave me advice, I was able to make the proper decisions.
My suggestion to you is to finish college, do well and keep HEALTHY! (Very stringent medical checks: not just the eyes) Then, when you pick a school, look at its advantages and disadvantages. Some can give you false promises. When your goal is to become an airline pilot, then see if the school will lead you to that.
PALav: can lead you straight to flying for PAL but its a battle getting in there.
Clarkav: depends on the demand for A320 pilots(Cebupac). Since they offer a different license MPL, this could make it hard for you to get in if you are not sponsored by Cebupac.
Flying schools and colleges: We have some good flying schools but its the hours that are important and you don't have enough when you graduate. You either have to fly in genav, be a flight instructor or pay your hours yourself.
Anyway, good luck and let me know if you have any more questions. There are a lot of good people in these forums any they will help you out.