Is it permissible for a man to propose to a woman during her `Iddah(waiting period)?
It is impermissible to propose to a woman in her `Iddah, but there is no harm in making an implication to such an end in case she was observing it due to the death of her husband.
What is the ruling on not fulfilling a vow?
A vow is a commitment towards Allah, The Almighty, and so, it should be observed as much as possible, and it is impermissible to take it lightly. Allah, The Exalted, says –in commending the believers-: “(Because) they perform the vow and fear a day whereof the evil is wide-spreading,”{Al-Insan/7}.
Is it permissible for a woman to apply Kuhul(Halal eyeliner) and go out wearing it?
Kuhul is part of a woman`s adornment, and it is forbidden for her to show that to anyone other than a husband , or a Mahram(Unmarriageable kin).
Is it disliked to clip one`s nails at night, and is it permissible to burn them afterwards?
It is desirable to bury the cut hair and the clipped nails. As for burning clipped nails, there is no evidence forbidding that , but it is better to suffice with the aforesaid ruling-burying cut hair and clipped nails-as it is based on a well known evidence.