How is the 180 day's rule affecting this?
-Her I-485 was filed based on NIW I-140 and thus, she can change any time.
if the job tile and employer changed, should the I-140 still be valid?
-It does not mtter to the I-140, but the I-485. Yes, the I-485 is valid as long as the job is still in the same/similar area.
Should the I-485 applicant informs USCIS of this change?
-Not necessary. Up to you.