You can add to the menu by editing includes/templates/westminster_new/templates/tpl_modules_mobile_categories_tabs.php.
If you want to move the categories, information, contact us, etc to just below the top navigation bar you will edit the includes/templates/westminster_new/common/tpl_header.php file.
Code:
<!--bof handheld menu display-->
<?php require($template->get_template_dir('tpl_modules_mobile_categories_tabs.php',DIR_WS_TEMPLATE, $current_page_base,'templates'). '/tpl_modules_mobile_categories_tabs.php'); ?>
<!--eof handheld menu display-->
You might also need to make some css adjustments.
Thanks,
Anne