Is Zakah (obligatory charity) due on the Zakah money received by a poor person, and reached a Nissab (minimum amount liable for Zakah), and a whole lunar year had lapsed over having it in his possession?
Yes, the poor who possessed a Nissab for a whole lunar year is obliged to pay the Zakah due on that money even if it was given to him as a Zakah money in the first place. And Allah Knows Best.
Is it permissible for a woman to ride a taxi without a Mahram (unmarriageable kin) in order to attend a gathering of knowledge?
It is permissible for the woman to pursue the knowledge that she needs in order to perform the religious requirements due on her if there was nobody to teach her at home, provided that there is no temptation involved. Moreover, we don`t recommend that she rides a taxi without a Mahram although such an act isn`t from the forbidden Khulwah (seclusion).
What is the torment of the grave?
We seek refuge in Allah from the torment of the grave. The important point is that the cause of the torment of the grave is disbelief or committing sins without repentance. It affects the soul, and the body is impacted by it, even if we do not see it. And Allah Knows Best.
What is the ruling on having a second congregational prayer in the mosque?
All perfect praise be to Allah, The Lord of The Worlds, and may His peace and blessings be upon our Prophet Muhammad and upon all of his family and companions It is disliked to have a second congregational prayer in the mosque which isn`t visited by travelers like the neighborhood`s mosque, and which has an appointed Imam, save with the latter`s permission. Nevertheless, if the mosque is visited by travelers, it is permissible to have a second and a third congregational prayer, whether it has an appointed Imam or not, or whether he permits that or not. And Allah Knows Best.