CA website replication

Our existing website is located at http://www.cabulldogs.org. This project, for a new website, must replicate it completely and identically. I want to use a CMS, possibly Joomla. The website must be up and fully functional as a side-by-side comparison and the final step will be moving it to the live URL, which will be identical to the existing URL. Every, single element absolutely must be replicated, from hyperlinks to images, to content, etc. I DO want to change any mailto links to an actual form. Many users these days no longer use a mail client, including myself, and the mailto links as they sit do not work if you only use an online client. CMS management will be multi-tiered and allow for multiple site administrators, as well as individual administrators/contributors/managers within each school. Our school district (Columbia Academy) is a private Preschool-12th grade school consisting of several segments: 1) Preschool; 2) Lower School; 3) Spring Hill campus; 4) Upper School; 5) Spring Hill preschool (future); as well as individual administrative areas (IT, Executive, Business Office, Facilities/Maintenance, Cafe, & Sports). Each of these segments should have a separate sub-site that we can work with for different subdomains (e.g. - [login to view URL], [login to view URL], etc.). I will probably need to adjust the project requirements to meet any questions I receive; however, the person/group awarded the project must understand - this project is required to fulfill these requirements before payment is rendered. Upon final inspection and prior to migration to the live site, a portion of the fee will be paid - but the site must be 100% identical to the existing site at that point (with the exception of what I've named above, like mailto links replaced with forms). Please don't hesitate to ask any questions for clarification. Also, I do not purport to be a web developer, so you may have to "hold my hand" through some items so you understand what I want and I understand what you can do.