the back to catalog link is on the webassist/plugins/catalog/details.php page
Most all page content is in the webassist/plugins folder
the webassist/plugins folder is grouped pretty well by what the plugins are for
catalog display pages like results and details are in the catalog folder.
shopping cart related pages like the view cart and the checkout form are in the shopping_cart folder.
pages related to the side menu are in the side_menu folder.