Columbia is my (close) second choice, my first being MIT - if I were to receive an acceptance from Columbia I’d be fully happy to attend, even if I’d received offers from other schools (including MIT). Given the slim chance that I receive an offer from either of these schools (let alone both), applying ED to Columbia and EA to MIT (and others) seemed like the best way of maximising my chances.
As for the internship, it started last year, and will finish in my junior year of college.
I’ve looked into Rice (and really liked the school’s ethos) - if I qualify for application fee waivers (which I haven’t got round to checking yet), then expanding my list to include even more wonderful institutions becomes a viable option. Involving myself with NASA would be incredible, but so far the only direct route I’ve found is getting into Caltech, who offer SURFs at JPL for international students. The US seems to offer a variety of internships with commercial aerospace firms, so if accepted into a US college, those sorts of opportunities would be what I’m looking for.
I’d also like to thank everyone for their advice, it’s been immensely valuable.