Easiest is to use a Boole object, it takes two objects and adds or subtracts them depending on the settings. You want the default A subtract B setting. A would be your cube B your text (probably an extrudeNurb).
There was no floor in that example, if you put one in most of the chunks don’t reach it, they just get close. If you want near physical reality you’d have to use Dynamics or Clothilde or SilverBullet or something that would do Rigid body collisions.
well shatter has a built-in “floor” but if you want chunks… it sounds like you are using Explosion FX, you could make the explosion happen in X and Z only (‘not Y’ setting) and turn gravity off for the deformer then get the object(s) to drop by hand (like this) keyframing or with Dynamics or Clothhilde or whatever.
Make the text spline editable, from there you can move the spline parts or you can use Split to make the parts separate objects depending on how you want to animate.
Some deformers don’t have a range they have an amount but others do, it sounds like you’d want to use the Explosion FX deformer if you don’t want to have separate pieces.