I’ve seen contradictory information in different places; has it been determined if these 97SE theatrical mixes are the same as the on the 97SE laserdiscs (apart from codec, bitrate, and possible attenuation of the surrounds)?
I believe so.
Also, was the sound completely/majorly remixed for 2004 DVDs, or is the 2004 mix largely the same as either/both of the 1997 mixes (apart from obvious changes like Emperor, Boba Fett, etc.?)
Yup. If you have the DVD, listen to Tarkin and Leia right before Alderaan explodes, you will hear strange leveling issues that aren’t present in the 97 DTS track.