page template for attachement page?

WordPress supports several types of attachment templates. The function get_attachment_template in wp-includes/theme.php provides this support; it is called in wp-includes/template-redirect.php. If your theme includes attachment.php all of your attachments will be rendered with that template. If your theme also includes image.php then all of your images will use that template as long as they have a post_mime_type of image/*.

It is certainly possible to add gallery navigation. See wp-content/themes/twentyten/loop-attachment.php which uses functions previous_image_link and next_image_link.

Twentyten’s attachment template does call comments_template so you can collect comments on each photo. You just have to make sure your post links to the attachment pages and not directly to the images.

You can call is_attachment to determine whether the queried object is an attachment.