First, set your extrudeNURBS depth to 0. Now you can get the squares (or mostly squares) by going into the caps tab of the extrude object and selecting Type>Quadrangles, and then checking the “regular caps” option. You’ll probably have to lower the width to get a more regular spacing.
Now you can blow it give it some depth and blow it apart with the Explosion fx deformer. This has a spherical falloff, but you can minimize that by scaling the deformer up quite a bit. r10 file is attached here: https://www.3danvil.com/temp/squares_fly.zip
You would have to do some point-level editing if you want to make the object 100% squares.
There are other ways to do this with Thinking Particles or MoGraph, but AFAIK the method I used in my file is the simplest way.