I have a site that's nearly 10 years old (therefore I want to be careful about not breaking inward links and not affecting SEO page ranking).

So initially I've installed Drupal (fortunately there were no clashes with existing directories) and rather than tinker with the root .htaccess I've created a new .htaccess in each first level subdirectory, each containing just

DirectoryIndex index.htm

This has worked well. Not only are the index.htm files visible, but other .htm files within these directories also no longer cause a 404 error. And I've been able to set up pointers to these pages in my new site's menu.

Is this the 'approved' way of doing it, or is there a better way? I've not found any articles on this.

And obviously eventually I'll want to migrate the old content so it has the new look+feel, sidebars etc -- is that as simple as setting up a node with a url alias foo/bar.htm?