If a husband and wife have been living separately for more than 6 months, and the wife requests Khula, is the Iddah period mandatory for the wife? If so, what is the correct way to observe it?
Bismihi ta'ala
Yes, the 'iddah period must still be observed by the wife, even though a long time has passed from their separation, as long as she is not ya`isah.
It is three menstrual cycles, and she does not necessarily need to do anything. The only thing she cannot do at all is get remarried during this time.
Please refer to detailed Ahkam books for further explanations.
And Allah knows best