You don't need to logoff -- the advantage of not loggin off is that when you come back, you will be immediately recognized.
Hardly anyone uses the Log Off -- which is why it's in such an inconspicuous place.
Breadcrumb trail is the term for a hierarchical display of sections that a lot of websites use. You put them above the page content to help people navigate back (like chickens back to the hen house).
For the forums, the breadcrbum trail is
Home page > Section > Thread name.
A lot of sites use it with their index page and content sections.