Why log in? Logging in lets you reserve a nickname so no one else can use it, and lets you be counted in future player rankings on the site. Other players only see your nickname, not any of your login information.
The current draft version of the third expansion, Innovation: No Place Like Home (aka "Cities"), is now available. See the FAQ for more information.
The rules are available online. The rules for the Echoes of the Past and Figures in the Sand expansions are online as well. You are strongly advised not to use the expansion until you're familiar with the base game.
You can discuss Innovation strategy at the Board Game Strategy forums.