E commerce website required

Website Brief
The website will be designed in two stages – the initial stage to get a more basic site up with artwork looking professional if not simple, and the second stage which will be getting it looking really good. The bid is for the first stage of the website build.
Site to have E Commerce that needs to have API and will need to match up with one of the main platforms such as Magneto (preferred), OS commerce or Zencart.
Site needs to be search engine optimised, and ongoing SEO tweaking is desired but not essential - this will be paid as extra.
Any work done after the website has been initially setup will be paid as extra.
Site needs to have content management which enables the following: adding or deleting pages, adding or deleting products with their associated information and photos.
Each product needs an equal sized small photo that can be expanded by the website visitor to see a larger photo of the product.
Site needs membership sign up option
Each product needs a review section that can be modified by members
Slideshow of photos and artwork on homepage.
Under construction page whilst website is being designed.
Logo will be provided.
Youtube video on homepage

Webdesigner requirements:
Website designer needs merchant website experience.
Webdesigner to be able to offer ongoing consultation, design work and troubleshooting after website has been designed
Tools to measure competitors’ SEO strength (and our own) desirable but not essential