Dear Andy,
Thank you very much for your input. They are all very valuable points.
# Place title and meta-data directly under the content-type meta tag.
--> I'm trying to find the way to do it in Typo3# Move scripts to the bottom of the page (just before </body>) as they block parallel downloads and rendering.
Which script, can you please be more specific?# Don't use <b> to style text. Either use <strong> to give emphasis to the text or simply a <span> to style it.
# Remove empty paragraphs. Instead, use margins.
# Remove <br /> tags that aren't breaking up text.
# Construct elements only used by JavaScript through JavaScript.
--> Absolutely!
# Don't use <img> to mark up graphics. Use CSS (background-position) instead. (Look at your testimonials). <img> tag should be used to mark up images related to content, not graphics.
--> I will remove the image and put in CSS

# All <img> tags should have a non-empty alt attribute.
--> Correct.
# You may only have one <title> tag. Your services, portfolio and contact pages has two.
--> Thanks for spotting this out.
# Navigation menu lacks a heading.
Is this a site navigation you mentioned or top nav?
# Start combining files. You have 8 external javascript files, 6 external stylesheets and 17 background images. Combine the background images into a CSS sprite.
# Enable caching by adding Expires headers.
# Enable gzip compression.
With regards to the header and top navigation, I intended to put them right after main content.. hopefully, it would be better for SEO. Instead of loading the same content everytime, I just want Google find the unique H1 and content straight away !?