As for the second point, I'm not sure whether internships really create an appreciable advantage at elite schools. Based on anecdotal evidence and some cursory research, I would posit that most qualified applicants to elite schools will have one if not two internships for major organizations. Many will have done academic research. I know a guy who is attempting to get his research on binary star systems published (his first choice is MIT). Careers start early.
Internships are definitely desirable things to have, I don't think that they differentiate students. If anything, they are a prerequisite. Trying to get into college is hard. From what I've experienced, I'm not sure if enslaving oneself to the cult of standardized tests is worth it. The OP seems to have a fair idea of what he wants to do, and has a non-trivial amount of ability. He should think critically about whether or not college is worth it.
I would definitely not endorse the long, arduous process of maximizing attractiveness to colleges during one's high school career in the unequivocal way that you did. One's career aspirations and expectations are highly personal things.