If you plan to set up an LLC you should probably do so prior to moving forward with the website for numerous reasons not only liability but tax wise as well. Anytime someone sets up a new business I advise speaking to an attorney.many attorneys will quote you a flat fee to sit down and ask as many questions as you may have. You also may want some help i forming the LLC and they can advise you as to how to proceed with that.Although you may be capable of setting it all up it is always best to speak to a professional about the specifics. Especially if the webiste has the potential for such issues as you state (i.e. defamation etc)