Yeah #12 pretty much lists everything. The only thing I'd add to that is that because it's a Japanese disc, you need to use an Action Replay, modded console, or Japanese console to play it.
That said, you can ALSO run the game in an emulator like Cassini, and depending on your hardware (doesn't take much these days) it will run superior to the Saturn (i.e. at full speed).
1. The audio is ADPCM so it's better than the PSX's XA-Audio. Most people won't spot the difference though.
Well, when I was compiling my custom soundtrack for my ipod, I did notice some differences. The two definitely sound different, but you have to mix a Saturn and a PS1 track together to hear it. I personally prefer the PS1 myself.
In addition, some tracks were changed with little riffs or modifications, but most of these weren't good additions if you ask me. A few are listed on the Dungeon, but you've got to have a good ear to find the others (Tragic Prince has a riff, for example).
Overall, the game's not worth it unless you're either (a) a collector or (b) a REALLY REALLY REALLY hardcore SotN fan (i.e. you play the game like three or four times a year without getting bored) or (c) find it for like $40 or less (and there, mainly for collector's value).
Otherwise, the DXC version is probably the definitive, despite having to buy cables for your PSP to play it on the big screen

Note you can also download the PS1 version to your PSP. (BTW, how different is the audio in the PSP one? Has anyone done a side-by-side analysis?).