The content of the pages you create are stored in the mySQL database rather than as static files so you cannot just see them if you look through the directory. The software reads out the data from the db when requested and renders it according to various settings.
As for editing your wordpress pages/entries using an external editor, wordpress supports an XML RPC interface which can be used to communicate with it. For an example of an emacs extension to edit WP articles, check out http://www.tolchz.net/2008/01/06/posting-to-wordpress-with-emacs-webloggerel/. I'm sure many other editors have this facility as well (including, I'm led to believe, Microsoft Word).
Finally, if you want to use the web interface but use your own editor for the textboxes where you edit pages/articles, check out the it's all text plugin for Firefox.