Let me try to answer your questions
When a new member joins they are automatically in moderation for their first 5 posts. Those posts will be released when a mod/admin for the forum the posts are written in are online and able to release them. Unfortunately it may take awhile before they are released. If the 5th post has not been released yet, any subsequent posts will also fall into moderation as well. I hope that makes sense.
Until the 5 posts have been passed through moderation, a new member cannot pm anyone except a mod/admin, cannot join chat, nor can they join a social group. Once they have had their 5 posts passed, they can then do all those things. Please keep in mind that sometimes the servers may be a bit slow in recognizing a new members 5 post status and give it a bit of time if need be before telling a team member of any issues with joining chat or social groups.
I hope this clears up the mystery

sabby