Separate Setting for Approval and Delete
 

Is it possible to separate the setting for image approvals from the one for image delete? We want to have approval emails on, and delete emails on during moderation, but does that mean that if we do a big clear out we'll end up sending out hundreds/thousands of emails for deleted images?

Separate setting these are separate actions entirely. Each action will send an email regardless of whether you approve or delete an image thats up to you. If you do not want to send emails on deleting a photo you need to edit all your different scripts that can delete an image and remove the mail from being sent out on a delete. I beleive adm-misc.php editphoto.php and adm-photo.php all send an email when a photo is deleted.