The universal 3D look of anything is an interesting idea, there is a lot of research, but this is something which if very far from the idea of OS. Ideally, it should not be a part of OS at all, or can be some of the replaceable outer shells of OS. To get some ideas, read this:
http://en.wikipedia.org/wiki/Microkernel[
^].
As to the requirements, the question goes nowhere in principle. You did not share any definitive ideas on this matter. The different sets of such ideas could be very different, hence creating very different requirements. You cannot put a carriage in front of a horse. :-)
—SA