Yes. You can rename it at WP Admin->Settings->MultiLevelNavigation->Menu Content tab->Modification->Titles.
Yes. You can add your own items using the Custom Code function. E.G. Just set your "Menu Item" as Custom 1 or something and place the following into Custom 1.
Are you sure you have the Multi-level Navigation plugin installed? I tried to visit your site, but I just got a 404 error so I couldn’t check it for you.