XML in Microsoft Office 12

Interesting but vague article on XML in Microsoft Office 12:
http://news.com.com/Microsoft+adding+XML+files+to+Office+12/2100-7344_3-5728536.html?tag=st.prev

They are going to XML as the default formats. In addition to the normal 
benefits of XML (you can get at the data easily in a lot of ways and do 
data integration), they say this will dramatically decrease their file 
size,  reduce the risk of corruption, and reduce the risk of viruses. 
They  no longer seem to believe that this can not be done in a 
performant way. And they will also publish their schemas.

Couple of questions:

1. Anyone know whether these will be cleaner schemas than the ones used 
in the current documents?
2. How significant is the move to XML as the *default* format, as 
opposed to another available format? I guess it's really pretty useful 
to be able to just use the files on the hard disk without converting 
them first.
3. How many of the reasons from moving from a binary file format to XML 
also apply to binary XML in web messages?

Jonathan