Questions[derivatives](ubuntu)

There were so many discussions about an Ubuntu with RR. They were so many pros and contras. At the end ubuntu wont be changed, the 6 month cycle system wont be changed. Thats fine!

But because there are so many people who would like to use an ubuntu with RR Im asking myself why isnt there an Ubuntu Derivate with RR. I couldnt found one, there are a loooot of Ubuntu Derivates but no RR. Is it just impossible? I mean Ubuntu = 6 months cycle, so the derivate have to be a 6 month cycle too? Is there no other option? Or are there already some smart guys trying to solve this problem? Thank you!

I sometimes see the expression of Vanilla Ubuntu but I cannot find what it means.

What kind of version of Ubuntu is Vanilla Ubuntu?

The four main desktop environments are GNOME, KDE, XFCE and LXDE. While Kubuntu and Xubuntu are considered official derivatives of Ubuntu, Lubuntu is not. Why is that so?

Update: Lubuntu has gained official status in 11.10.

I want to ask if we're gonna see a version of Ubuntu such as Kubuntu for example but with GNOME shell and not with Unity ? A version called something like Gubuntu. Thanks in advance for your answers :)

What different Ubuntu derivatives are there? And what is special with them?