When my son applied this past February, everything that they needed YOU provided. Unlike the academy application itself, where you have to have your counselor verify your extracurriculars, or your principal your academic info, and have a sealed transcript mailed directly from your school, for NASS they took everything you provided at your word.
So yes, if your school calculates it, you will need to know your rank and how many in your class. Your test (PSAT at least or ACT, SAT) scores, GPA (weighted and unweighted), and any academic awards. But most of the application was "fill in the bubbles". Like "varsity sport yes/no", "community service yes/no". No way to really show something like "I had 150 hours of community service". Even like "Club officer yes/no" didn't give you any way to show what you'd actually done. I believe there was a short box after each major section in which you could expand on your answers, but it was very limited. You will be giving a very brief summary of your life so far!