For above players:
%player.setShapeNameColor("R G B A");
The colour should be in decimal RGBA format, and the alpha should probably always be 1. Don't know if it's required or not.
If you don't know how decimal colour works, say so and I/someone will explain.
For chat, there are probably several ways you could go about doing it, the easiest being to change serverCmdMessageSent to be absolutely terrible and use messageAll instead of clientCmds like you should and changing the name colour. I feel like a gigantic turtle stroker suggesting it though, so someone else should explain the right way to do it.