The issue with the insert not saving the ID is that the insert was failing because no default image was set and you weren't specifying an image after validation. You can't maintain the file upload field value after failed validation, so they will have to re-browse to the uploaded images they want if the validation fails.
You should probably add server validation for the image or allow null to prevent it from failing the insert and still redirecting.
The update page was using the form POST value to filter the recordset. The server validation clears the post, so it can't maintain the recordset state and show the image. The solution is to save the value in the Session and refer to the session variable for the recordset parameter. I've updated the page to use that technique for the first image, you can use similar code for the others.