Joomla Website Loadtime Optimization

Please see http://www.testgenie.com. Homepage will do. Site is implemented in Joomla. Right now site is not optimized and has significant load time. I am looking for long term partnership with a freelancer to work with us achieve optimal results. 1. Apply css sprite on images to reduce number of images in Joomla template. Module images not to be touched for now. 2. Modify or replace mod_roktabs with jQuery based slider to reduce loading mooTools on front page. 3. Modify/Combine four modules in one - Login (HighSlideJS based), make it based on jQuery - Signup (jQuery Based) - facebook like and facebook connect - few design changes permitted. 4. Minor cleanup on site design Possible feedback on following (But do not include in the bid) Feedback should include Yes/No, comment, and possible expenses if done. 5. Possible optimization on facebook .. [login to view URL] . is there any? 6. Possible CDN on Amazon Cloudfront. I have already setup one in experimental setup but contents are not being cached in client browser. 7. Should we migrate to Joomla 1.6 or 1.7 (We have many core hacks in Joomla, so afraid).