Erlang Facebook API

I am exploring way to get into user's graph using Facebook API, my language of interest is Erlang. With quick search, unlike Yahoo API, I found couple of erlang module available to do the job. I will go over it and if I find anything cryptic, I will update it on next post.
My requirement

1. User wanted to bring their user graph but not need to provide their userid/password (oauth)
2. Once loggedin, they choose people who they are to be invited 
3. Choose selected one.

This is kind of interesting flow, in fact, others following.  

Constrains,

1. What is the API user agreement?
2. No of calls limit
3. Constrain to post message to Facebook using API
4. Retrieve Events 

I will research these topic and post it here if anything interesting.

[Update] Facebook API doesn't allow contact email addresses of friends but found that there are greater API level integration with different graph API. But clue is "it is easy with oauth" but facebook notoriously stoping me to verify my account using phone no :)  So I am hibernating this effort.