[Graeme Dice]

Is it possible to mod the monsters from some master list already on the game? Or do you have to write the file that mods anything in the game?

You can modify a specific monster by selecting that monster to modify in the text file.

And if the later is true (and unfortunately I think it is from my searching), does anyone have a list of everything in the game already written up for download? So I can just modify that?

The allview map contains every unit, so you can modify those by the appropriate commands. See the Troll mod on Illwinter's site for an example of how to do this.