This depends mainly on content analysis and how deep you can dig in the texts you will aggregate. You definitely understand then the langue(s) difficulties, so my suggestion is to focus on one language as a starting point. If you have developed good enough psychological dictionaries that will make your work less difficult.
my advice is to make a proper sampling of the profiles you want to investigate. The only challenge then is to measure how "liar or honest" the person is about what she/he is saying. actually this is my challenging question that i am working on now. so far i can tell you that it will be solved :)
good luck with your work, and please keep me updated. I am interested. (my thesis is about "identity construction on facebook"