I need help with the length of some MP3s.

[Lion King]

you have to edit the fade times in the id666 tags if it still fades. highlight a spc file in the playlist editor and hit alt+3.
i can't believe though that your spc files have fade times set in the tag but not playing times. disabling the fading for files without tags works fine here.
are you using the latest version of snesamp (3.05)?