Drupal in subfolder, clean urls and images (htaccess not quite right)
The ultimate goal here is to get any request to the base domain (http://www.example.com) redirected the drupal subdir (http://www.example.com/drupal), correct? Why not just remap everything to the subdir and let Drupal handle the www. prefix and clean-url mapping?

RewriteCond %{REQUEST_URI} !^/drupal
RewriteRule ^(.*)$ /drupal/$1 [L,R=301]