Maybe create a plugin the does uploading and provide the proper hooks for other plugins to use it?

Yes, we could start with very simple plugin, even not a multiple uploader to start quick; just the isolated code from the current. And then (let other community members) provide fancy alternative with more and more features.

Hi, I do not know if this has been asked before or not.

Some of my users have asked if a function to rearrange the order of pictures in albums can be developed.

I think this is an important fuction, allowing users to change the way the pictures are displayed in an album.

Or simply drag and drop the order.  Really anything that will allow a user to change the order.