Is it permissible to pay the Zakah (obligatory charity) for settling the debt of a deceased relative?
It is impermissible to pay the Zakah for settling the debt of the deceased since Zakah is paid to eligible recipients who are alive. As for the debts of the deceased, they are to be settled from the estate before dividing it amongst the heirs, but if the deceased didn`t leave an estate, then it is desirable for his/her heirs to settle those debts if they can afford them. And Allah Knows Best.
Is permissible to buy/sell with non-Muslim?
Yes buying/selling for a Muslim with non-Muslim is permissible as regards what is lawful.
Does passing wind, from the anus without a smell, invalidate prayer?
If a person is certain of having passed wind even if it was with no smell, then both his/her ablution and prayer are invalidated, thus he/she should remake ablution and re-perform prayer.
I`m getting old and haven`t got married yet. I love wearing the veil, but people advised me to take it off because it could stand in the way of my marriage, and that I should wear it after getting married, what should I do?
The veil (face drape) is the wear of the Prophet`s (PBUH) wives and righteous female companions (May Allah be pleased with them) and whoever imitates a certain group of people shall receive the same reward or punishment like themselves. Only those who are religiously poor deny women wearing the veil, and thinking that it stops a woman from getting married is from the evil suggestions of the devil.