Is it permissible to visit one's father at his uncle's house, knowing that the son's mother has invoked a curse upon anyone who visits the father in that place? And is it permissible to recite a surah after Al-Fatiha in the third and fourth rak'ahs of prayer?

You are obligated to visit your father and maintain ties with him. Your mother's refusal to allow you to visit him is not to be obeyed, for there is no obedience to a creature in defiance of the Creator. Her supplication against you will not be answered. You must treat her kindly, advise her, and inform her of your father's right over you. There is no harm in visiting him without her knowledge.