Re comments crew might have "heard" the missile detonation. Quite unlikely with supersonic shrapnel impacting cockpit area in advance of the sound wave.
True, but there would be the sounds from the shrapnel impacts - hence the 'sudden loud noise'. Depending on exactly how fast the CVR lost power, there might be some initial sounds of decompression/breakup as well, but we're talking small fractions of a second. The "WHAT'S THAT" would be if one of the pilots spotted the approaching missile.
All in all, it's unlikely the FDR/CVR will tell us much of anything we don't already know (or at least strongly suspect).