After exhausting all of my Deferment and Forbearance options on my loans, I have applied for IBR.  Once IBR goes through and payments begin, if my income changes and I experience hardship, will there be any other Deferment and Forbearance options?

Deferments are available under certain circumstances, for example when a borrower is in school at least half time.  Economic hardship and unemployment deferments have a 3 year time limit.  But it’s possible that some deferment conditions that might not apply now could apply later.

There are two kinds of forbearance: mandatory and discretionary.  There is more about that here: http://studentaid.ed.gov/repay-loans/deferment-forbearance

But remember - if income goes down, payments under IBR go down too, and can be as low as zero.