The "sand the flywheel" is to de-glaze it.
Note in the pilot bearing removal : If you don't have an "internal puller", another method I have used is to find a wooden dowel ( or make one ) that fits thru the pilot bearing. Fill the back of the bearing with grease from a grease gun, then insert the dowel and give it a good whack - the bearing should pop right out. ( clean up the greasy mess, wash your face and change your shirt )