Pen - I understand it's very easy, though being lazy I paid VW do fit it as the cost was very reasonable. Not having the steering wheel controls will not be an issue.
I have not decided a price yet and want to wait until the Zenec is fitted before selling the other unit anyway, but I will put the details here when I do.
Derek - Don't know about the background colour, it looks black from the pictures I've got, which is fine by me. The only thing that I'm not 100% on is the fact that the buttons will be white illumination, not red. As to the reversing picture, I don't know - mine never did that, so never been worried about it.
I'll post an update here once the Zenec has arrived and let you all know, plus some pictures of what it does.