The possibility of dual layer DVD function is interesting, but it would require a nav unit that physically has this capability. So I presume that it is something that will be possible on a future nav computer. Though it is curious as to why they would introduce it for a MK IV system that is non i-drive, since it is slowly (if not already) being phased out (or to use BMW's terminology, I understand introducing it for the NAVI03 system since that is i-drive based, but not the non i-drive "DVD Top-NAV" system).

No idea about the voice files.