MapTool integration

I have an idea on how to start, but there are parts I'm at a loss on. Here are the requirements:

MapTool, available at http://rptools.net/, is a Virtual Table Top application for RPG games as well as table top other games. One of its features is the ability to place a repository if images on a website for download, thus saving the person hosting the game from uploading it to each player. For this feature to work, there must be a specially formatted file located on the server (at the root of where the images are stored). This file is generally called index.gz.

The contents of this file when uncompressed is the MD5 hash of the file, a space, then the relative path to the image, and a new line.

Requirement 1: I need to generate MD5 hashes of all existing images in the Gallery.
Requirement 2: I need to generate MD5 hash for new images as they are added.
Requirement 3: I need to generate a new index.gz after each image is added.

The save files for MapTool are xyz.cmpgn, xyz.zip, and xyz.prtok. These are all zip files with the images stored in a folder named assets. The images are stored by their MD5 hashes, without the file type extension.

Requirement 4: I need to extract the assets folder of MapTool archives and add these images to the Gallery.
Requirement 5: I would like to store only one copy of an image on the website per MD5 hashes.
Requirement 6: The file names either need to be given extensions or the image type needs to be detected by the image file content instead of treated as generic data.

For 4 and 6, I figure I can make a custom version of ArchiveUpload. But I'm at a loss on how to do the others.

Thanks,
IMarv