I want to move that site to wordpress so I have more flexibility to add updates
You can either recreate your site in WordPress or you can have your html site with the posts from WordPress showing up in a window on your main html page or showing up on a linked page. Either way, you have to install WordPress.
WordPress will not take over or absorb or assimulate your site. You can take your html pages and post that code into Pages in WordPress. Pages in WordPress are for static information.
I tried want you want to do with a previous site. I eventually found if I wanted to use WordPress correctly and to my advantage, it was better to covert the entire site to WP. With my current site, I still use DW for all the html, changes to the style sheets, even additions/deletions from php files.
I am one of thousands that WP 2.7 works perfectly for me in every aspect. If I were you, I would install the default theme in a sub-directory and try it out. Make changes to the CSS. Experiment.