Also, for Parent PLUS borrower deferment. If I quit paying my student loan, what will happen to my requested deferment?
if you stop paying your loan before you've been notified that your request for deferment has been granted then your deferment will not be approved and your loan will become delinquent and you may go into default.
and what if I'm eligible for the deferment and rolled for at least half-time?
In most cases, your loan will automatically be placed into a deferment based on enrollment information reported by your school.