But this is their website. Wasn't that easy enough?
One thing though, the MacBook Air doesn't have a Retina display. The new MacBook and MacBook Pro models do, but the MacBook Air doesn't.
Here are the specifications for them:
http://www.apple.com/macbook/specs/
http://www.apple.com/macbook-pro/specs-retina/
http://www.apple.com/macbook-air/specs.html
They don't make specific mention of 64 bit CPU architecture, but that almost goes without saying. Apple hasn't used any 32 bit processors other than the very first Intel models introduced almost a decade ago.