All I want is a plugin that allows lighting like how the torches make orange, lightning makes blue, and the moon makes sort of bluish... What the plugin would do: Allow a person to switch the glow effect of the torch to a different colour (Instead of always orange, you could colour it to blue, red, green, purple, etc...) Something like the Colorful Lighting Mod, but a plugin that allows torches and glowstone to be able to change the light colour that they emmit. Colourful Lighting Mod Thread: http://www.minecraftforum.net/topic/617400-colorful-lighting-mod/
The fact that all rendering is done client side makes it impossible. I believe texture packs can support altered lighting (since the colours are pulled from a file) but this would be a client mod and not a server mod. If you mean you can change colors on the fly (meaning torches can give off different colour light in different areas or something) that's not possible at all without some huge client modifications.
This. The lighting system in Minecraft isn't built for different color lighting. Yes, it might seem like the sun is colored differently from torches, but beyond that you'd need to completely rewrite the game's lighting code. For further confirmation, look at the official RedPower FAQ: EDIT: Also, the client mod you linked to hasn't been updated since 1.7, which means it wouldn't even work under the games new lightning system.