A lot of new chat users (myself included) begin by asking someone in the room how to use the chat system. I think an easy-to-find link to the chat "Frequently Asked Questions" page would help people feel more comfortable. There is a link in the chat room itself, but it's in tiny blue lower-case letters at the bottom of the page.
I propose adding a link on the Help Center > Privileges page, in the description of the privilege. It would look something like this:
20 talk in chat Participate in this site's chat rooms.