What is the ruling on performing istinja' after passing wind from the anus?
Ablution is invalidated by passing wind from the anus, even without a smell. Only ablution becomes obligatory from it. Istinja' is not obligatory nor recommended. And Allah the Almighty knows best.
What is the ruling of Islamic Law on someone who wakes up in a state of janābah (major ritual impurity) near the very end of the prayer's designated time, during cold weather — should he heat water in order to perform ghusl, even though the prayer's time will expire as a result, or should he perform tayammum instead?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
If the water is cold, and cannot be used due to fear of harm that is not ordinarily tolerable, or that would result in illness, then in this case it becomes obligatory to heat the water — even if heating it causes the time for Fajr to expire — and no sin is incurred in doing so, due to his valid excuse. He may not resort to tayammum (dry ablution) instead, since water remains available [and merely needs to be heated].
Imam Shihāb ad-Dīn Aḥmad ar-Ramlī (raḥimahullāh) said: "He was asked regarding a person who, if he were to use cold water, would experience harm that permits tayammum, and who has access to something with which he could heat the water — but if he heats it, the prayer's time will expire. Is it obligatory for him to heat it even if the time expires, or should he pray with tayammum within the prescribed time? He answered that it is obligatory for him to heat the water, even if the time for that particular obligatory prayer expires." [Fatāwā ar-Ramlī, Vol.1/P.98]
Imam al-Bājūrī (raḥimahullāh) said in his Ḥāshiyah on Sharḥ Ibn Qāsim (Vol.1/P.173): "And if he fears [harm] from using cold water, and is currently unable to heat it, but knows of a place where firewood is available, such that if he were to go there he would not return until after the prescribed time has expired — what appears [to be the correct position] is that it is obligatory for him to go and seek the firewood, even if the time expires as a result, as this is the position ultimately settled upon by ar-Ramlī, and as related from him by Ibn Qāsim." And Allah, the Exalted, knows best.
Is Zakah due on the orphan`s money?
Yes, Zakah is due on the money of the orphan.
What is the ruling on the follower (*maʾmūm*) reciting Sūrat al-Fātiḥah behind the imam?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah.
In our school of Islamic thought, the Shāfiʿī school, reciting al-Fātiḥah is obligatory in every rakʿah of the prayer for the imam, the follower (maʾmūm), and the one praying individually (munfarid), because it is one of the pillars (arkān) of the prayer. Whoever does not perform it, his prayer is invalid, whether the prayer is silent (sirriyyah) or audible (jahriyyah), based on the saying of the Prophet (peace and blessings be upon him): “The prayer of the one who does not recite the Opening of the Book (Fātiḥat al-Kitāb) is invalid.” Agreed upon.
It is stated in ʿUmdat al-Sālik, one of the books of the Shāfiʿī school: “He recites al-Fātiḥah in every rakʿah, whether he is the imam, the follower, or the individual worshipper.”
The jurists of the other schools hold a different opinion, which was previously explained in Fatwa no. (3169); please refer to it. And Allah Almighty knows best.