This excel file might be helpful:http://www.finalfantasyiv.net/host-files/hacks/MagicCompendium-R1.xls
This is my magic data compilation workbook most of the raw hex data came from the Bab-il docs and from some of you guys...probably JCE and/or Dragonsbrethren.
I defined all of the Sound Effect bytes from 0x00 - 0x7F (I don't think 0x80-0xFF are valid). Please excuse my craptacular descriptions of the noises (I tried to provide examples where possible). However some spell animations have hardcoded sound effects that seem to ignore the SFX byte.
I also got along pretty far in defining the Visual Effects but I kind of got bored with it and never finished it all.
I did manage to make a few new spell effects by playing around with a test ROM but I never did anything with it. I did think about changing the L3 elemental spells to use the appropriate "Fang" elemental item graphics and make them "target all" spells similar to what Zozma is doing; however I wanted to modify the L1 and L2 spells as well but I wasn't sure what (if any) monsters actually cast these spells in battle...so I was still researching it. It is totally do-able and pretty easy. The palette byte is definitely all that needs to change for Zozma's spells to look right.
It can be kind of fun to play with, like you can add a screen shake to spells that didn't have it and so forth. However some spells require both the 0x02 and 0x03 visual effects set properly to work right, for example flare and holy (holy is somehow hardcoded special when you set it's effects), you kind of just have to take a ROM and trash it by playing around with the spells and see what happens.
Anyway, it's not a totally complete document but there it is FWIW.