I have this site that is more than 3 years old and has some decent rankings in the search engines for a wide variety of keywords. However, the site is designed very poorly as it was the first site I made when I was first starting out in webmastering and was done in WYSIWYG in Dreamweaver. What I did was to create several templates, one for each category and then uploaded articles using the relevant category and gave it their own urls using the title of the page.
However, what I would like to do now is to redesign the site in Wordpress. The last time I only used parent categories and then added articles, but now I would like to add several sub-categories assigned to each parent category so its easier for the user to navigate. But I would like to maintain the existing urls because it already has good amount of traffic.
So, my question is, how can I create subcategories and assign the existing articles to these subcategories rather than the parent category and still maintain the existing urls?
Also, since the site has around 500 or so pages, is there a way to import it without having to manually assign the articles to their respective subcategories or will they need to be done individually, in which case I am probably looking at week's work, not to mention the repetive nature of the task.
Any help appreciated. Thanks