Modify and clean up HTML files and CSS files to make W3C/HTML5 compliant & optimise for SEO keywords

I have created a website based upon a template. In the process of modifying/customising the template various errors have appeared on Dreamweaver when the 'Validate' button is pressed. The site works perfectly just it's obviously not up to W3C standards. I also need the 'Recent News' section on the bottom of [login to view URL] to be replicated in the same place over several more pages. The website is [login to view URL] My exact requirements are: 1) Replicate the 'Recent News' section on the bottom of [login to view URL] on to [login to view URL], [login to view URL], [login to view URL] and [login to view URL] 2) Clean up the HTML/CSS of the whole site to ensure W3C compliancy (i.e. when you click on Validate in Dreamweaver no errors are found). 3) Carry out one off optimisation of website for SEO words as follows: energy algarve, air con abuse, air conditioning abuse, high air con bills, high air conditioning bills, energy saving, algarve energy saving, air con sensor, air conditioning sensor, tfd2000, tfd4000. 4) Provide me with the html/css files for me to upload back to the server. Many thanks. Rick.