CSS, HTML, W3C, accessibility

I'm planning a restyle of my site and, before proceed I need an HTML, CSS and W3C expert who find any problems and suggest the right way to solve it. I would like to have some suggestion about accessibility and usability for the site. The site has about 500 pages, but many of those use some templates so that when you solve a problem in one page, you solve the same on every other pages that use the same template. So there are about 50 pages to check for problems and 2 master templates that are used on every page. About what to check on every page I need in general to have a report for every error/warning html, css and w3c. About CSS use and corrections: At the moment I use many CSS and I want to use one file only in every pages of the site. I have to find all inline CSS tags in html pages and plan the way to be place them on external css. The CSS files are actually too large and I want to strictly simplify the file and make the site more accessible for every browser. I want to know where in my site is possible to use sprite instead of many images to speed up the download. I want to know where can I get some more improvements like the ones above. As a final job I want a detailed report explaining every problems on each page and the way to solve it so that I can give it to my technician and solve all and any improvement that could be done on the entire site and on single pages. You can use automatic tools for that or manual. I'll give the website url to the interested coders to make an exact bid. To win the bid I would like to have a demo of the report you will give to me made on the homepage and your suggestion about other checks I missed and surely I missed something here because I'm not an expert in this.