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.
Is Zakah due on the orphan`s money?
Yes, Zakah is due on the money of the orphan.
A man cursed Allah, is he allowed to perform prayer without making Ghusl?
All perfect praise be to Allah the Lord of the Worlds. May Allah`s peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Cursing Allah is an act of apostasy and one who commits it must utter the testimonies of faith, make repentance, take back wife; however, it isn`t conditioned that he makes Ghusl (Full body ritual purification) to pray. And Allah The Almighty Knows Best.
Is it a condition that one should offer two sacrifices for a male newborn?
It is desirable to offer two sheep for a male newborn, and one for a female newborn. Offering one sheep for the male newborn is also permissible as it observes the Prophet`s Sunnah in this regard.