I am writing a android app that will pull in a list of all the users friends so they can tag them in the photo but displaying a large box of the friends with their photo ins
I recommend you the following class:
https://github.com/gajus/facebook-friend-rank
It give your friends a score based on user interaction:
'feed_like'
'feed_comment'
'feed_addressed'
'photo_tagged_friend_by_user'
'photo_tagged_user_by_friend'
'photo_like'
'photo_comment'
'friend_mutual'
'inbox_in_conversation'
'inbox_chat'
then it sort the list by score desc.
Hope it helps.