In answer to your first question, yes, one should be able to locate the playlist file for the stable release anywhere which the daemon can “see” it. The declaration in the configuration file is followed by a path statement. So, you could conceivably place it where you like as long as you declare the location.
The answer to your seccond question is an unfortunate and well documented “no”. Libraries shared via DAAP are read-only. Since playlists are part of the iTunes library hierarchy, it is not presently possible to create a playlist from shared tracks on a remote system — even if the playlist file is stored locally.
That said, unless I am mistaken, such functionality is a part of the long-range development plan for mt-daapd. The ability to create playlists may be integrated into the web administration interface for the daemon. Rescan and push functions will undoubtedly be part of that ability. However, unless Apple changes the support paradigm for shared DAAP libraries, one will likely not be able to accomplish such from within the application itself.