I see that someone has already mentioned Bulk Rename Utility. I second the recommendation for that. I started using it a few months ago and its a wonderful program.
For duplicate image detection, someone mentioned VisiPics. I used that for a while but eventually switched to SimilarImages (homepage:
http://celebnamer.celebworld.ws/similarimages/ ). I've found it to be easier and faster to use. The only issue I've had is it will occasionally hang if you're checking 50,000 or more pictures at one go. *whistles innocently* On the other hand, it has options for setting the level of similarity, prioritizing what criteria to use to flag for deletion (image resolution, file size, last modified date), limiting comparisons to only within same directory; only between different directories; or a standard "everything against everything" check. It will also build a "Not-A-Match" database. If you tell it that a given pair of pics are not duplicates, it will "remember" that and skip that pair in subsequent searches. This greatly speeds up future checks as you continue to build your picture collection.