I am new at this, and currently have a site that is php. I tried installing the google webmaster sitemap but keep getting error messages. My friend was saying that maybe I don't want google to index many of my pages because they are dynamic and if someone finds them the info would be outdated, and that person could potentially buy something that wasn't there anymore.
...I suppose what I'm asking is: 1. Is a downside to a sitemap? and 2. Is possible to enter pages/files of a dynamic site that are only available after a member logs in?