Change PHP Theme to Responsive PHP Theme

Take an existing theme and transform it into a responsive styles theme. Twitter bootstrap. I own a site that offers free image downloads but it is built in PHP but the template theme is not responsive. I wish to make the theme I am using responsive plus add some additional touches. 1. The theme should be responsive to 5 popular sizes. Widescreen PC, Normal PC/MAC, Laptop, Tablet, iPhone 2. Theme should allow for a 300px wide sidebar at all times. 3. Header logo auto reduces (automargin?) 4. Navigation bar changes from buttons to drop down choices. 5. Footer is text, no problems there. 6. CSS file must be neat and clean. 7. When a device chooses to download, only the size of the device used can pick the image size. Example: PC/MAC can have all sizes, but when a device smaller than 310px chooses a download, it only has those choices. This site offers free downloads so my captcha code must remain in place. Contact me to view the site BEFORE you place a bid.