XML Data Islands, XML Menu Trees and other stuff

I have to do a research to my boss involving a lot of XML technologies to try to
define a path for future developments.

My aim is to try to define the most platform independent solution i can, away
from MS and if possible not very Java dependent. So i'm looking to XML/XSL, and
since you are all such a great guys (~violin music~) i'll ask for your advice.

I've been looking at XML Data Islands but don't understand what it is really. Is
it a MS only feature or is it a W3C definition? Can i treat XML Data Islands
with XSL?

The aim here is to have portions of a html page been updated without a trip to
the server, refreshing the all page.

I saw here in the list people asking about building tree-like menus out of XML.
Are there any examples i can show my boss?

What good IDE's are for XML/XSL, with visual capabilities?

And if any of you has some ideas about XML/XSL (and CSS/CSS2) techniques toward
a platform-independent solution please give me some points.

Thanks to all for your kindness (~violins again~).