i million
No, I don't think so but, you will need to look it up.
Yes, you can. All xbox 360 accessories (av cable, ethernet cable, memory unit, controllers, etc.) and games work with all versions of the xbox 360. The only exclusion I know is the HDMI cable which only works with Xbox 360s with built in HDMI port (all xbox 360s versions currently being sold have HDMI ports).
a lot
As of April 19, 2012, 67.2 million Xbox 360 consoles have been sold worldwide.
It is already.
Microsoft said that they sold 10 million units in the first year before the Wii and PS3 were available. Total Xbox sales in January 2011 was 50 Million and PS3 is 48 million
Whew, as more are being sold every week (and possibly every day) it's impossible to tell exactly. Based on figures from the NPD Group, as of November 1, 2008 Microsoft managed to sell 11.6 million Xbox 360s in America. (2008 -11-01)[update] That number is probably much higher by now. If you were asking about the sixth generation Xbox console, according to Microsoft as of May 10, 2006 they had sold 16 million in North America before the console was discontinued.
no it is available at many locations
50 million have been sold by January 2011 see related link
Yes, and only sold for the Xbox.
If you count a router cable as a ethernet cable, yes. An ethernet cable is what you plug from your xbox into a laptop/router/modem to connect to xbox live. The following SKU's come with ethernet cables. *Xbox 360 PRO *Xbox 360S *Xbox 360 Elite The xbox 360 CORE and ARCADE have no ethernet cables. Hope this helped.