Is it permissible for a woman to lead other women in prayer?
Yes, it is permissible for a woman to lead other women in prayer. The most knowledgeable among them in the rulings of prayer should act as the imam. She should stand in the middle of the row, slightly ahead of the others.
Is Zakah (obligatory charity) due on owned land?
Zakah is due on the land used as an article of merchandise and was originally bought for that end. Zakah is due on it at the end of every lunar year. Its value is estimated, and (2.5%) of the total value of all such lands owned by the questioner is given as Zakah. However, no Zakah is due on the land used for building a house, or an agricultural purpose.
What is the ruling on using a miswak (tooth-stick) during the day in Ramadan?
It is permissible to use a miswak before noon while fasting. However, according to the Shafi'i school, it is disliked (makruh) after noon in order to preserve the natural effect of fasting in the mouth, as the Prophetﷺ said in authentic hadith:
"The breath of a fasting person is more pleasant to Allah than the fragrance of musk."
When is Istikharah (guidance prayer) Du`a offered, before Tasleem (saying asalamu alikum warahmatu allah wa barakatuh to end the prayer), or after it?
It is offered after Tasleem.