It's not uncommon for those of us who find ourselves overwhelmed in one language to attempt to make our expertise takeover the unfamiliar territory.

You seem to be wanting to have the categories show when the site opens and nothing else. For this, you could create a "dummy" category with Desktop Lamps, Mobile, Floodlight, etc as subcategories. Have Zen open directly to the dummy category (switch in the admin) and it will show as you have it now. Clicking on Mobile would then take the customer to the products in that category.

Just a thought.