This was done because one of the “qualifications” to be a “dreamer” was to have a high school diploma. That’s why it was retroactive as well. Not enough of the illegals could be bothered to pass the exam so it was eliminated.
Yes, but you could also be in some sort of school, such as a GED class, and get it. You don't ever have to actually graduate or get the GED, just keep enrolling in a class when you renew.