Create custom modifications for the Chevereto image hosting script.

We currently have several domains that are image hosting sites, they are all based off of the chevereto image hosting script. We would like to have some modifications created for them. We would like the following, paid memberships, ability to password protect libraries if the user wants, subcategories, ability for users to add tags and titles when uploading images and change or add them from their control panel, a rating system. The code for this should be clean and secure, the script is very light and to the point, so all of the mods should be fairly easy to implement. We will also need instructions on how to add these mods to all of our sites so we can implement them our selves. If you have any questions about any of the mods please let us know. Good Luck and Happy bidding.