Wow! That's a lot to try and plan for. The first thing I would ask, is why you want to be an A&P? Is it to work on your own plane some day? Is it because you think it will help you understand aircraft systems? Do you think you can fall back on that, if you get furloughed from an airline? Do you want to be a bush pilot, run your own svc, and work on your planes?

I think you need something like 1900 hours of experience to become an A&P, and after all that, you won't make much money doing it. Most A&Ps try to get jobs in heavy maintenance or at power plants, which pay well and have more job security. So unless it is something you REALLY want to do, I don't think it will help you much at all as far as either being a pilot or having a back up career. However, it may help you to work at an FBO and trade work for flight lessons.

To get an ATPL in Europe you need to take something like 14 tests and it definitely will not be cheaper to learn to fly there, ALTHOUGH, as an EU citizen, university will most definitely be cheaper than in the US.

Since you are in HS, why not explore the Civil Air Patrol or Young Eagles? You will get an early exposure to aviation and in the YE, you will probably meet some very experienced A&P's. Right now there is a growing shortage of them, because just like regional pilots, they've been underpaid for too long.