As for the saves no is not exactly what happens, quoting Ren'Py site itself:
So now you have the files both in the saves subdirectory but also in the hidden directory like beforeWhen possible, Ren'Py now stores save files with the game, as well as in a user-global save directory. This means that if a Ren'Py game is placed on a USB drive or shared on a network, the saves will be available on multiple computers. (When save files are available in both places, the newest file wins.)
When a save file on a network share is updated, Ren'Py will automatically rescan the contents of that file, and restart the current interaction. (This will update the save and load screens, making the file available to be loaded.)