What is NHS and CSF?

I don't live in CA, so I don't know about the second thing you mentioned, but you apply to NHS through your school (usually at the end of your sopre year). You have to show that you've done a substantial amount of volunteer work before then, and demonstrate the leadership roles you had in a few of those activities. When/if you get in, there's usually a service requirement (at my school, 15 hours a semester) and a leadership requirement (either starting your own volunteer project or going to some sort of seminar). It definitely looks good on your college application, and it's not a horrible time commitment.