Its white in the GTD and yes you can turn the red strip on the door down. Im not sure about the sills. I have mine set as bright as possible, I lurvvve it!
The pictures above emphasise the colour a little more than it is in real life. There's a post on what you like about your golf and everyone agrees irrespective of which spec they have that the night illumination inside the car is a thing of beauty. Id be surprised if you don't like it when you get to see it in the flesh.