Is man given free will or is he predestined? And what is the implication of there being a book that describes a person's life before his birth? And did Allah Almighty speak to Moses and Muhammad (peace be upon them) in Arabic, even though the Qur’an had not yet been revealed during the time of Moses (peace be upon him)?

Man is both predestined and given free will. He is predestined for what he was created for, and he is given free will because he has been granted intellect, hearing, and perception with which he can distinguish. What is written when the soul is breathed into the body pertains to one's happiness or misery, and each person is facilitated for that for which he was created.

The Messenger of Allah, peace and blessings be upon him, said: "There is none among you, and no soul that is born, but its place in Paradise or Hell has been written, and it has been written whether it is wretched or happy." When he was asked: "Should we not then rely on our كتاب (predestination) and abandon action?" He replied: "As for the people of happiness, they will be facilitated to do the deeds of the people of happiness. And as for the people of misery, they will be facilitated to do the deeds of the people of misery."

As for how Allah spoke to the Prophets, it is not known to us, nor in what language it was, but we believe that He spoke to them directly, without an intermediary.