(collaborative) XML support?

Hello *

I found Amaya .. and, on the first sight, I found it really great.

Instead of editing HTML however, we would like editing XML
(that needs to be transformed into HTML) ideally the transformation 
result should be displayed in a WYSIWIG manner.

=> is that possible?

Furthermore, we are interested in collaboratively working on such an 
XML document. Ideally, the changes should be version controlled.
(whenever committed - checked in, if no conflicts occur)

=> do you support this feature? 

Alas, no modest requirements, I know. But probably there is a good
potential to contribute, if you could help us, and if it's not too much
work.

 Klaus