Folder Permissions?

I am not quite sure on how to set these permissions this certain way that people would like, if it is even possible. How would I set up folder permissions that would allow you to do these;

-Allow users to edit files in a folder but not create or move files to that folder

-Allow users to move files from folder but not delete files from that folder

Moving files out from a folder would be in a way deleting them would it not? It has me a bit confused on how to go about doing that. Any ideas on what I could do to do that would be appreciated.