Is the `Iddah (waiting period) of the divorced effective from the time the divorce took place, or from the time of registering it at the court?
It is considered effective from the very moment her divorce took place, but not from the time of registering it at the court. And Allah Knows Best.
I`m married to an American citizen who used to be married to a man in Mexico and filed for divorce there. It is worth pointing that in America she isn`t registered as married. When she arrived in Jordan, her lawyer called and told her that she got the divorce, and based on this we got married in Jordan. What is the ruling of Sharia on this?
All perfect praise be to Allah the Lord of The Worlds. May His blessings and peace be upon our Prophet Mohammad and upon all his family and companions.
You haven`t mentioned whether this woman has converted to Islam or not. If she had embraced Islam and three menstrual cycles passed, but her first husband hasn`t converted to Islam, then her relationship with him is over. If you married her after this (Passing of three menstrual cycles and first husband not having embraced Islam) then your marriage is valid. However, if she didn`t convert to Islam then your marriage contract with her is invalid and you have to wait until she gets divorced by her first husband and observes Iddah, which is three menstrual cycles. Afterwards, you can conclude the marriage contract. We pray that Allah doesn`t hold you to account for what you have done because you thought she was divorced. We recommend that you seek Allah`s forgiveness as much as you can and do righteous deeds. We also advise you to marry a Muslim woman to preserve your and your children`s religion since Almighty Allah Says (What means): "Wed not idolatresses till they believe…" [Al-Baqarah/ 221]. It is true that marrying a Kitabi (One who believes in a book of sacred scriptures and with whom a Muslim may marry in what is deemed a lawful marriage) is permissible, it involves great risks, as stated in the aforementioned verse. And Allah The Almighty Knows Best.
I wish to Pray at the Mosque, but I couldn't because I am a Woman. How can I get such a Reward?
All perfect praise be to Allah The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions Abdullah Ibn Masood (May Allah be Pleased with him) reported that the Prophet (PBUH) said: "Her prayer inside her home is better than its courtyard, and her prayer in her own bedroom is better than inside her home." [Abu Dawood]. Her staying at home, and not going to the mosque in obedience to Allah`s injunctions entails a great reward similar to that bestowed on a man for going to the mosque since the Mercy and Blessings of Allah Prevails. And Allah Knows Best.
Is the father a Mahram (Non-marriageable) to his son`s mother-in-law?
The father is a non-Mahram (Marriageable) to his son`s mother-in-law, so it is impermissible for them to look at each other, or to have a seclusion (Khalwah).