Build an Online Store

I would like to have a nice designed website with at-least 3 changeable themes (Main Theme)(Christmas)(Black Friday) I need to have an easy control panel where i can add/remove categories and subcategories I need a place to add a banner on the top so i can change/add deals banner on the right with the hottest 5 items Users should have an easy signup process Easy add/remove items and change the numbers of items left in stock It needs to have a cart And please who ever is going to work on this, i need to understand how to setup a bank account or a paypal to setup the purchase system where you can buy directly online from the site and calculate the shipping cost based on the address. And if there is an easy way where i can send adds and email deals for all the users that are on the database. Kindly send me any questions you have. Possibly who ever is going to work on this that i will continue to work with in future upgrades for the fact that they already have a complete idea about the website.