Is it permissible for the young woman to turn the suitor down if she had no feelings for him?
Yes, it is permissible for her to do so.
What is the ruling of Islamic Law regarding one who purchases a sacrificial animal (uḍḥiyah) and it then develops a defect before slaughter?
Praise be to Allah, and peace and blessings upon our master, the Messenger of Allah.
If a defect that invalidates the sacrifice (uḍḥiyah) arises after its purchase — for example, if one purchased a sound, defect-free animal, and it then developed a limp, blindness in one eye, or a similar defect before slaughter — it does not fulfill the requirement of a valid uḍḥiyah, according to the Shāfi'ī school.
It is stated in Asnā al-Maṭālib fī Sharḥ Rawḍ al-Ṭālib (Vol.1/P.535): "Even if the limp develops [in the animal] while the knife is upon it, it still does not fulfill the requirement, because it is lame at the moment of slaughter — this is analogous to a case where a sheep's leg breaks and one hastens to slaughter it [in that condition]."
The Ḥanbalī school, however, held that if the one offering the sacrifice purchased the animal while it was sound and defect-free, and a defect then befell it afterward, the sacrifice remains valid and there is no obligation to replace it.
It is stated in Masā'il al-Imām Aḥmad, one of the Ḥanbalī reference works (Vol.8/P.4021): "I said: If a person purchases the sacrificial animal while it is sound, and it is then afflicted with illness, blindness in one eye, or a broken limb [before slaughter]? He [Imam Aḥmad] said: It is said that it still fulfills the requirement. Isḥāq said likewise, because he purchased it while sound, and the defect befell it only afterward, so it remains sufficient on his behalf." [End of quote]
Accordingly, a sheep afflicted with a defect that invalidates the sacrifice does not fulfill the requirement of a valid uḍḥiyah — whether the defect arose after purchase or during the slaughter itself — according to the Shāfi'ī school. However, there is no objection to following the Ḥanbalī position on this matter [as a valid alternative]. And Allah, the Most High, knows best.
Who is "the poor" entitled to receive Zakah (obligatory charity)?
The poor is the one who has neither money nor a source of living, or has either of them, but it isn`t sufficient such as being in need for a hundred/JDs, and having an income of forty/JDs only.
Is it permissible for the children of a deceased father to settle his debt from the Zakah (obligatory charity) money due on them?
It is impermissible to use the Zakah of one`s money for settling the debts of the deceased. However, children should settle the debts of their deceased parents out of filial piety. And Allah Knows Best.