>Is there a program that lets me rename lots of pics?
It's called a batch renamer, there hundreds of them and it's nothing remarkable. Check out Sourceforge.org
and you should find something.
Just don't expect anything extremely advanced; I've yet to find one that can rename based on directory path and image dimensions (ie, "./Series/Volume 01/Chapter 006/file.jpg" -> "series-vol01-ch006-p###" where page increments in sequence by one except where width is greater than height).