What is the due amount of food in expiation for perjury? 

It is feeding ten indigent persons: 600 grams (for each) of the average food of your families such as rice, and it is permissible, according to Imam Ahmad Bin Hanbal, to give that amount in money if it was more useful to them.

How long is the` Iddah (waiting period) of a divorced woman?

If a woman is pregnant at the time of divorce, then her 'Iddah (waiting period) expires when she gives birth to the baby. If she is in a state of menstruation, then her `Iddah expires when she finishes three menses. However, if she doesn`t have menses, then her `Iddah expires after three months. And Allah Knows Best.

Sometimes I receive a message containing a picture of someone desecrating the Noble Quran. The sender asks recipients to send that message to their contacts as an act of defending the Quran. What should I do when receiving such messages?

Praise be to Allah, the Lord of the Worlds.

You don`t have to circulate that message, because this isn`t the proper way to defend the Quran. And Allah The Almighty Knows Best.

Is Zakah (obligatory charity) due on articles of merchandise even if they were stacked in the merchant`s stores for years?

Yes, Zakah is due on stored articles of merchandise even if they were stacked in the merchant`s stores for years because this is the way Islam has countered monopoly.