ownership drupal directories Would it be safe to say only the files directory should be owned by apache user ?

I have mine set files apache:root

And all other drupal directories root:root ?

My permissions are set to 755 for everything excepting 444 on settings.php

Actually my files I've set to 775 and have 
in www chown -R root:apache html 

then chown -R apache:root files
It would be safe with all folders being in 0775 and settings.php in 444.
However, if you would use FTP/SFTP to edit either the themes or any module files You may need to login with the "Owner" user, which may or may not be possible in a shared hosting environment.

So., depending on that you may choose. However, if you use SSh it will be not an issue.