I had a quick look at your website and some-what understood your changes :-)
But it would be great if you provide the existing CMS information, probably with a test username.
a. Whether is done in PHP or .Net or any other software?
b. Open source or Proprietary CMS?
I trust the above two questions does make difference in time and cost estimation.
Expecting your early reply
Could you let me have a link or some more details about what your after.
Are you able to share a link to your site?
Please let me know the extent of changes required so that i would be able to quote on this project.