Ecommerce Shopping Cart with Paypal Checkout

I'm looking for a very simple shop to plug into my wires website - she is not trading yet but we need this asap.

Must have function to:
Add/Edit/Delete stock
Add/Edit/Delete Categories
Add/Edit/Delete Sub Categories
Change P&P options
Add promotion codes - £off or %off
Export stock DB
Manage stock levels

Need to check out with Paypal for now but plug World Pay in come January. So need that option please.

I can design and provide any html pages - i just need the shop / cart / checkout programmed.

Please see designs of how i'd like this designed....