Create PHP Web funnel template using PHP-Include

I want a funnel created along the lines of a squeeze/lead capture page but created using includes so that the content of the page can be changed dynamically and to suit any file meeting set criteria. The funnel would include index, oto, downloadpages and would consist of predefined areas on the php page for inclusion of either text, images or optin forms depending on page/position. These elements are not interchangeable and would require set criteria so lets say a header image was included, then that image might be for any report/product but would be a set width/height etc. The oto would consist of a matrix of cover images, again scaled to a predefined size and then the download pages would reflect the choices made in the first two pages. Every element that might change would need to refer to included php files and the var function would be used for title, name, call to action etc.