yep, Flash, haha.
cheers.
We like Flash because it's basically just a timeline. Birdo is the studio who worked on the character animation. Their approach is based on traditional cel animation (drawing each frame), but utilizing the playback speed and clear intuitive workflow available in Flash. Obviously, they know how to do animation- the tools really don't make that big a difference. :)
Flash was also used for the animatic.
Indeed, After Effects for compositing. Spidem Essence for espresso.

Depends, really. Almost all of the big 3D creation softwares (XSI, 3DS MAX, Maya, Cinema 4D, etc) are pretty much equal in terms of power. What mostly differs is ease of use and different key features. There isn't really a right/wrong issue here, in my opinion.

For example, from my experience 3DS Max as an easier user interface than XSI, but some XSI versions offer powerful built-in keying software for special effects. One of my friends uses Cinema 4D and the lighting he's able to pull off always stuns me, which is something I don't think I'm able to squeeze off 3DS Max. I've never used Maya.