Jimmy,
I got into Purdue (started 2001 graduated 2005) with a 3.7 high school GPA and a 29 on the ACT as an out-of-state student. Given the fact you are a sophomore in high school, you've got PLENTY of time to build your resume. I think extracurricular activities & sports will help your admissions chances; I played football, was in National Honor Society and was the resident school A/V geek (an odd combination I know) and it certainly didn't hurt me any!
I think the best thing you can do, honestly, is keep getting A's in your classes and keep making yourself a "well-rounded" student. Those standardized tests SUCK, but obviously the higher you score on either the ACT or SAT the better off you will be on that (IMO) exceedingly useless means of comparison.
You can easily double-major in both aviation and the Krannert School of Management (many have done this), but I think Aviation will be the hardest of the two to get into. Another option is simply attend Krannert and do your primary flight training at Lafayette Aviation your first two years of school, then transfer into the Flight program after your Sophomore year as a double-major.
Good luck!