The original thread (in the old Video Software area) is here.
So a couple of days ago I somehow miraculously stumbled upon something which could do exactly what I wanted - it's called ayumilcv.exe and it can handle both the original Peace@Pieces graphics files and those of the fan disk (but just the graphics files - GR.0xx and PIC.0xx - BGM.0xx would spit out the .bin files which I assume are further-archived normal sound, but I couldn't figure out how to get them into a playable form; TP.0xx wouldn't open at all).
It wasn't too hard to figure out how to use the tool (although I found that to work right I did have to run it through AppLocale because I've not had my comp in Japanese codepage mode for a couple months), but I just want to be absolutely sure that what I chose was the best option - or at least what I thought it was. This is the interface:

I'm assuming the three options in the center there are something like 'Save all as/Convert all to BMP', 'Save all as/Convert all to PNG', and 'Save images with alpha as transparent PNG, everything else as BMP' - at least that's what it does when each of those are selected, respectively. I can also assume that the box directly underneath that is simply where one would choose the level of PNG compression, as I've seen that feature and scale before in other places.
The ones I'm the most stumped on are A) the window title; B) the text above the progress bars; C) the right-most button underneath the progress bars, which didn't seem to do anything and could just be toggled on and off. I know one of the two buttons at the bottom clears the field above it (which displays any error messages or warnings, etc. that arise), but I don't know what the other one does.

