I applied for three boarding schools... what are my chances of getting into them?

I applied for Choate, Exeter, and Andover.
My SSAT score is 2310. Is that score good enough to get into these schools?
What weighs the most – interviews, essays, grades, teacher recommendations, or SSAT?
How selective are Exeter, Andover, and Choate? What do you need to be able to do to be chosen for these schools (because I know a lot of geniuses apply to these schools…) ?

I spotted a small misconception in your comment. Interviews, essays, grades, teacher recs. and SSAT scores will all play into the admissions process, but you’re forgetting about ECs, awards, financial aid status, race, legacy and nationality. All of the things you listed are pretty important, but if you have a hook (recruitable athlete, full-pay, URM, parents went to school) then that is likely more important. A 2310 on the SSAT is great for applying to all of these schools. A/E/Choate are all very selective, (Andover, for example, accepted only 13% of it’s 2013 applicants) and yes, almost all of your fellow applicants will be bright, well-rounded students. This doesn’t mean that you won’t get in, and it doesn’t mean that you will get in. Admissions is a bit of a crapshoot, especially if you require F/A. Good luck!