- avoid "id" (use page or something other instead) - as long as your link structure doesn't change, also the PR will not change. PR is calculated from the link structure. As long as the structure isn't changed it doesn't matter if the pages are called index1.htm, index2.htm, ... or index.php?page=1, ... - since PR just depend on the structure, it is also independent from directories
link structure means how your pages are connected.
Take a sitemap and draw an arrow for each link on each page. As long as this structure is unchanged it does't matter how you name a page, where it is located or if it is dynamically generated or static.