edit the Security Assist Authenticate User server behavior that is on the login page.
On the Session tab, click the plus button and select the Users name column to store that in a session.
On the page you wish to display that, go to the bindings panel, expand the session collection and add the user name session to the page.
to redirect after a period of inactivity, you would need to add custom coding such as using the following JQuery plugin to track activity:
http://www.paulirish.com/2009/jquery-idletimer-plugin/