I have done a similar project with one of my sites.
All you really have to do is to create a separate php file that has the navigation information in it than insert the call tag into every page. The hyperlinks should be a full pathway your site
I will implement a design that will make your sitewide links editable in one file, And option to change the header, footer, background, and various other aspects of the site. Whichever you specify.
I can complete the project in 1-3 working days.
Thanks,
Bucky