Does the clipping of nails nullify ablution?
No, it does not, and it is preferable to wash the hands afterwards.
What is the Islamic ruling on eating from the 'aqīqah?
All praise is due to Allah, and may peace and blessings be upon our Master, the Messenger of Allah.
It is recommended (mandūb) to eat from the 'aqīqah, unless it was vowed (mandhūrah). If the 'aqīqah was made as a vow, then it is prohibited to eat from it, and it becomes obligatory to distribute the entirety of it in charity to the poor. And Allah Almighty knows best.
Is it permissible to divide a single Sa‘ of Zakat al-Fitr—or its equivalent value in cash—among more than one poor person?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
Zakat al-Fitr is estimated at one Sa‘ per person, but the number of people to whom this Sa‘ can be given has not been specified. For this reason, it is permissible to distribute a single Sa‘ among more than one poor person. And Allah the Exalted knows best.
Is it permissible to delay the ritual purification (ghusl) from major impurity (janabah) until after dawn?
Yes, it is permissible to delay ghusl from janabah until after dawn, as purity from janabah is not a condition for the validity of fasting. However, one must perform ghusl in time to pray Fajr within its designated time.