It is over a year that nobody answered you and probably the questions are answered (?).
The following plugins will deliver an overview for the maintenance of orphaned pages and media files.
orphanswanted: http://www.dokuwiki.org/plugin:orphanswanted
Find Orphan pages, Wanted pages with reference counts. Also shows reference counts for linked pages
Loacte Orphan Media (Tips): http://www.dokuwiki.org/tips:locateorphanmedia
Sometimes you get to upload many, many files in your DokuWiki installation. Or you are trying to do some maintenance and save space. Anyways, you'll come to the point where you may ask yourself, “what media files are actually being used in my wiki installation”?
orphanmedia: http://www.dokuwiki.org/plugin:orphanmedia
Find orphan and missing media files.
Please add a solved at the beginning of your post headline in the event your whishes are solved.