Sorry that I didn't respond to your question quickly enough (I had taken a few days of vacation and wasn't online much in the past few days).
When you ask if you can send private messages, I'm sorry to say that you can't do that yet either. Facebook's API was in a state of change regarding that functionality at the time when Spring Social 1.0.0 was released and so I purposefully left it out until the API had stabilized. Now that it has stabilized, I have it planned for v1.1.0, but have not yet started work on it. I know that's not the answer you're looking for, but...I will try to carve out some time today or tomorrow to give it another look and see if I can implement it. I'll let you know.
Spring Social Project Lead