The fast is not nullified by this, so he may fast.
Yes, it is prohibited, since it consists of unlawful chicken or parts of it, or it has at the very least come into contact with it making the soup Najis.
If it is another place of residence, then you should offer full prayers.
Kurr water equals in volume to 27 cubic hand-spans. Based on an obligatory precaution, the hand-span is equivalent 25 cm. In terms of mass, Kurr corresponds to 464.1 kg, and it is preferred to consider it to be 470 kg.