Earlier quoted context omitted.
Creating an app to extract Facebook contacts would be a piece of cake.
I don't think that's allowed. "III. Storing and Using Data You Receive From Us ... 7. You must not use user data you receive from us or collect through running an ad, including information you derive from your targeting criteria, for any purpose off of Facebook, without user consent." [1] I suspect that means you need consent from every user whose information you collected (your own list of contacts is made up of oth…
It's generally within FB's terms of service to store Facebook ids, but unless you're a larger company like Yahoo, I don't think you're allowed to do much else other than use the data for your app.