Does the deceased nephew inherit from his uncle who has no children and who died after the nephew's father? And do the sons of the deceased brother inherit from this uncle if their father died after him?

You do not inherit from the estate of your first paternal uncle because of the presence of your two paternal uncles, who are full brothers of the deceased. They are closer 'asabah (agnate heirs) and thus exclude you. The sons of your second paternal uncle do not inherit from the estate of your first paternal uncle because of the presence of his two brothers (your second and third paternal uncles). Rather, they inherit from their father's estate, which may include his share of what he inherited from his brother who passed away before him.