Legal Question in Intellectual Property in California

Yes, your name. Maybe if the art is your creation, or not. Maybe if you authorized the art through certain channels, or not. You need a specialized attorney in Cali to handle this for you.

Best of luck. I think those Cali lawyers are very good at what they do :)

Probably. Look at the Privacy Policy and Terms and Conditions on the website before you post. That will explain their policy about the use of material you post. In the case of most fan sites or forums, by posting you are agreeing that they can reuse the material you post in any way they want. I'm guessing you (as with most people) didn't bother looking at the terms and conditions or legal stuff before you used the site. It's a good idea to do that, especially if you plan to post information.