Basic E Commerce website - mock-ups provided

We are a small group of guys wanting to start a new T-Shirt Company in Australia, and we're ready for an E-Commerce website to drive the sales of our products. We have developed a mockup of the website and attached it to the project proposal. Like any E-Commerce website, we require a strong front-end which allows us to manage inventory, add T-Shirts (and images, sizes, quantity, price and a description) and deal directly with user accounts and invoicing. We would like to stick with a minimalistic design which keeps users on the same page as much as possible - we don't want them to be stuck jumping around from page to page and having to browse through a bunch of stuff in order to find their desired shirt. Instead, we want the main website to consist primarily of two sections. Section 1.) The main page. This is the page that the user is presented with when they reach our website. (See the top half of the attachment for a mockup). Our T-shirt designs will be separated into categories (which must be able to be customized, should reference the T-Shirt items etc. directly) and displayed on the front page. The top 12 of each category will be listed (we should be able to customize this in the front-end) with the option to "browse more in X" where X is the current category. When a user clicks on a design that they like, they will be presented with a pop-over window showing a close-up of the Shirt design and a gallery which changes pictures when they mouse over. On the right-hand side should be room for a description as well as information about T-shirt sizes, quantity and price. This is where the "add to cart" button should be. We also would like to include some "similar images" underneath the shirt. (Please see the bottom half of the attachment for a mockup) Clicking on the "Browse more X" button underneath the main page will take them to a separate page for each category, displaying each T-shirt in the same style as the main page. Clicking on them has the same behaviour as the Main page. Section 2.) The Check-out Check-out here is pretty similar to what you would expect on a normal E-Commerce site. We do, however, want to have the option to show the Shirts on a separate line for each one if they are a different style. For instance, buying 5 x Medium Shirts of Style Y just shows "Medium Shirt - Style Y x 5" BUT, buying 4 x Medium Shirts of Style Y and 1 Large shirt of Style Y will place the two different sizes on separate lines: Line 1 - 4 x Medium Shirts of Style Y Line 2 - 1 x Large Shirt of Style Y Users may choose to register or NOT, there is no reason to force them to register before purchasing. We would also like to include a shipping calculator on each page at the top (i.e: My Cart: x Items, $Y, $Z shipping) and inside the Shopping Cart. With regards to graphics design and supplying images of the Shirts - we already have a designer working on these, so this is not necessary for the project. We would, however, appreciate the creation of a basic scrolling gallery at the top of the main page (we can provide the necessary images or placeholders). Any other images, however, we can simply provide placeholders and deal with them ourselves. In terms of color scheme, we would appreciate some selections to judge for ourselves, but are leaning towards a darker feel. We do, however, need the images to "pop" out of the page so appropriate color contrast would be appreciated. As a final requirement, the website must pass W3 XHTML Strict validation where possible. We understand that some modules/add-ons may not be Strict compliant, but as long as non-standard code is completely avoided, we will be happy. Due to the simplicity of the project, this is a fixed price proposal. We would like to get started within 2nd week of January. A finish within the 3rd-4th week is preferred. If you completion could not be completed within this time-frame, please do not bid. From all the guys here, we look forward to working with you!