You can insert the categories into your navigation menu by going to Appearance -> Menus. Then simply select the same categories that are also on your menucard and insert them into the menu 🙂
We’ve set up the homepage like this: http://www.redfactory.nl/themes/therestaurant/2011/06/22/frontpage-widgets/. Take note of step 1. If you’ve set it up like this the breadcrumbs will be hidden automatically 🙂
Hope this helps!