Your playlist will definitely become blank if you delete the music referenced by it from your library.

If possible, you can try running iTunes from a new library location for doing some testing (you need to hold down a certain key sequence when starting iTunes and it will ask you where to create or load a new library from).

I don't really keep playlists, so I'm not the best person to ask about all their features in iTunes. If you can export the playlist then I suppose you can re-import it after reloading the music.