When you kill an enemy, a message shows up in red. When you gain an award weapon or use ShowMessageText, text shows up in yellow. When you get an award like War Hero, text shows up in cyan.

So my question is: can you output text like ShowMessageText does, but vary the color? Or, can you change the color in any way? Or is this hardcoded?

My guess would be hardcoded (last time i said that i was wrong ). The reason is (saying this as a beginner programmer) the text colors would be predefined in whatever they use to show message text. Then when it has the variable of what type the message is, it highlights the message before it "posts" it. So, if there is a way to do it at all, it may be thought a lua.

That's all covered in the HUD files, which are munged to ingame.lvl

I see - is there any way to change it per message? I want to spawn a few lines of text and be able to have them in different colors, not just one color throughout the entire map.

Not that I know of. You can't directly access the HUD files through lua.