Why are there items still on Magento after they were sold and have a quantity of 0?

The listing is preserved on Magento so as soon as you inventory another piece of hardware that matches the SKU criteria for that item the quantity is adjusted to 1 and the listing automatically gets pushed to eBay again. In other words, you only have to once link a product to a listing template in Magento and after that everything happens automatically from Razor.