mmhh, i would do it like this…
1.
first use the extrude nurbs tool witch makes ur Ai splines 3d, be sure u use illustrator 8 files when u export out of AI.
2.
I am not shure how experienced you are but then you could keyframe
the letters the make them spin.
3.
to make them change from lettrs to numbers or whatever, i would put them
in the same place and keyframe the visibility using the display tag.
btw: if the text is not that special you could use the build in text tool in the same workflow. just keyframe the text parameter. in this case you dont have to do the last step.
regards