How to convert images in a pdf file.

[Skyler14]

I have a few calculus textbooks which I have been reading on my Kindle for the past two weeks, but I have one really annoying problem. None of the images show up. I've checked and the images are all pngs. I've extracted all the images from the books, and need to replace the png images within the pdf with jpeg or whatever format the kindle supports. My textbooks have ALOT of special formatting for equations, so I would rather not try to do any more conversions than i have to (each time I've tried it has been a drastic failure).
These are the books:
http://tutorial.math.lamar.edu/pdf/C...I_Complete.pdf
http://tutorial.math.lamar.edu/pdf/C...I_Complete.pdf
http://tutorial.math.lamar.edu/pdf/C...I_Complete.pdf
http://tutorial.math.lamar.edu/pdf/DE/DE_Complete.pdf

So my questions are:
1. What free pdf editing application would meet my needs (be able to replace the images (preferably batch replacing) within the pdf files itself) and allow me to quickly get images working in these books on my Kindle?
2. What image formats and dimensions does the kindle support?