You can reduce the number of questions/answers in the Description field by changing the #3 setting for the form here:
Asana’s default CSV output includes a bunch of columns that you may or may not need; you can’t select them in Asana but of course in your spreadsheet use you can ignore them.
Or you can consider Asana2Go (disclaimer: I’m the creator) which offers the ability to choose two standard sets of columns, or to customize CSV output: