Blight

Is there any way to remove the green gas-like stuff that pops up around blight?

Yes. I can think of two different tracks to follow, though I cannot guarantee either in multiplayer. BTW, I'm not at my computer right now, and so unfortunately can't give specifics. First, there's a line someplace that refers to the frequency of the green puffs. Maybe in a txt file, maybe in a slk - I cannot remember off the top of my head - but I know I've seen that as a parameter someplace before. Set it to zero, and you're set (unless it's in miscdata, of coruse, in which case you're screwed). Second, look for a refernce to the texture used for the puff. I think I've seen it refered to again, perhaps in an slk file, perhaps by name in the image extractor. Either way, if you replace that texture with a dummy (0 kb) texture by the same name into the same path in your map, that should prevent the "true" texture from loading, preventing it from being visible.