What is the ruling of Islamic Law on making up missed voluntary prayers?
All praise is due to Allah, and peace and blessings be upon our master the Messenger of Allah ﷺ.
It is recommended for a Muslim to make up any missed voluntary prayers — whether the regular Sunnah prayers (rawātib), the witr prayer, or his personal devotional routine (wird). As for voluntary prayers that are tied to a specific cause or occasion — such as the eclipse prayers (kusūf and khusūf) — these are not made up once their time has passed.
Shaykh al-Islām Imām al-Nawawī, may Allah have mercy upon him, stated: "The correct view in our school is that making up the regular voluntary prayers is recommended." [Al-Majmūʿ, Vol. 4/P.43] And Allah the Almighty knows best.
What is the amount of food to be given to a needy person for fidyah and kaffarah?
The amount of food to be given to a needy person is 600 grams of wheat or rice.
According to the Hanafi school, it is permissible to give the monetary equivalent instead, and this is the ruling issued by the General Iftaa` Department.
What is the ruling on reciting the Chapter after Al-Faatihah , and what should a worshiper who forgets it do?
All perfect praise be to Allah, The Lord of The Worlds. Any other part of Qur'an that a worshiper reads after Al-Faatihah during the first and the second Rak`ahs is a Sunnah, and forgetting to do so doesn`t nullify prayer, and doesn`t require performing Sujood As-Sahw (prostration of forgetfulness). And Allah Knows Best.
Should the Zakah (obligatory charity) giver tell the poor recipient that this is the Zakah of his money?
No, he shouldn`t. But, the Zakah giver should make an intention in his heart that it is the Zakah of his money when paying it to the poor. And Allah Knows Best.