D2 vs D1

[steel]

I have been following this community on and off for about 7 years now 
(since college).  Revisiting it every now and then to catch up on its 
progress towards maturity. Can anybody direct me to where it is 
discussed or listed out what features in D2 break backward compatibility 
for D1 code?  Or, at least tell me if 
http://www.digitalmars.com/d/2.0/features2.html is up to date.  Also, 
what is the latest with regards to x86_64 bit support?  Other than LDC 
and GDC (which I suppose has fallen behind and is unsupported), are 
there any plans to support x86_64 with the dmd compiler and the D2 
release in the coming months (early next year)?  

I guess what I'm looking for is an honest assessment of the "state of 
the community" and information on a good tool stack to evaluate D for 
professional use in a x86_64 environment (IDE, build tools, etc).  

Final question: what is the role of Tango in D2?  I read something 
somewhere that lead me to believe Phobos and Tango have some kind of 
relationship in D2.

Thanks in advanced for any and all information.