Static files or dynamic WP pages for “static content”?

by

Put everything into WordPress. This way, you can search your entire content from the built-in search engine, and you can edit each piece.

If you need pages with special markup create templates for your theme.

Naked Template

<?php
/*
 * Template Name: Naked
 *
 * That’s the complete template!
 */

Basic HTML5

<?php
/*
 * Template Name: Basic HTML5
 */
?>
<!doctype html>
<meta charset="<?php bloginfo( 'charset' ); ?>">
<title><?php wp_title( '' ); ?></title>
<?php
while ( have_posts() )
{
    the_post();
    ?>
    <h1><a href="https://wordpress.stackexchange.com/questions/18080/<?php the_permalink(); ?>"><?php the_title(); ?></a></h1>
    <?php
    the_content();
}

Import

To import your old HTML pages use the plugin Import HTML Pages.