dynamic website how to....

Hi,
My question: I’m looking for a dynamic website solution and I’d like to know if I’d need to invest in learning php or if there is a simpler option for the following case.

What I want to achieve: I want operate many sites - a cluster of interlinked sites for improving the search engine placement of a main site. The sites are going to be basically about the same thing but each site must be unique in terms of page weight, content and appearance to avoid setting of any duplication alarms. I don’t want to write or maintain each of them one by one. I want to manage these sites from a central location without them appearing as duplicates to search engine spiders or to passing human inspectors. On top of that, it would be ideal if there was an automatic system for keeping the sites fresh (new content constantly) and for me to publish addition content/pages across the cluster in one action.

How I guess I could achieve it: I guessed that a combination of different looking templates, different external css files and dynamic content sections mixed up across the multiple sites could do the trick.

I would make each template and css file by hand I guess but the navigation would need to be generated dynamically for me to be able to add new pages or links to new sites across the cluster.

The content would need to be generated dynamically. Each site would have pages about the same topics that I could make unique by creating long pages from multiple paragraph sections. If I had say 20 paragraphs written on a topic each page could grab 5 of them randomly to create multiple unique pages about one topic. Periodically, the site could refresh by grabbing the 5 paragraphs randomly again.

How ambitious is that? Can you point me in the right direction?: I’m not a programmer, I’m a designer who know html. I’m willing to invest in learning what’s required to achieve this – php or whatever. How difficult is something like that to learn to program? Am I going to need to invest in full on programming understanding to achieve this or would it be as simple as learning html? Is php the best choice for achieving this as easily as possible? Do you know of any existing products, technologies, systems or services I could use instead (php was just my first guess).

Thanks
Ralf_the_cat