"message of the day"
Splash text. It doesn't change daily, it changes when you go into a server/world/open Mineraft~

you have to make them extremely dark with no saturation of color. It is grey-ish scale on my end. Everyone computer resolution is different, something you are seeing, someone else may not.

XXX

I am pretty sure the armors can be changed. you have to find the .png for the armors and just make them black and white. I personally am working on a texture pack and have changed everything for the inventories. The leaves blocks all you have to do is create a new .png yourself and it should update in your inventory. (add your own black and white) I recommend using Paint.net seeing as it has an auto black/white option tool.

The enchants on the other hand I think are just ingrained. I have yet to figure out where this is located.

-Ok so you need to edit the color map to get the plants black and white.
-The leather armor when being worn cannot be changed, but when in the inventory make the files labeled overlay the entire image and the other ones transparent
-the other things cannot be changed