Keep modules enabled/installed?
On Drupal 6, as per your question, you most likely do NOT need to keep node_export around after your content import/export is done.  It doesn't create any database tables and will only remove config settings variables when you uninstall. 

As for UUID it is (depending on  your settings) probably a good idea to keep it around.  It adds/alters some db tables adding its UUID to your content, etc. It would probably be less trouble to keep it rather than remove it and it shouldn't have an impact on the performance of your site.