> When changes are made from one user in ThumbsPlus or pictures are moved, how is it possible to keep the database up to date in realtime?
Normally the users would all have write access to the database and so, it would be updated whenever someone moves, copies or deletes an image file. You can also run TP on the server and have it monitor your image folders (Tree | Watch Folders) to catch changes that were made from outside TP (for instance, when someone uploads new images to a folder).