Is it permissible for a wife to give her money to her family as a charity, or a gift without asking her husband, or seeking his consent?
The wife has the right to give her money as a charity, or a gift to her family, or to other people after consulting her husband out of respect, and this is the meaning of treating on footing of kindness and equity. Therefore, if he wanted to stop her from helping her family, then there is no harm in not telling him.
I have a date farm, and the dates come in different categories, and within each category there are different sizes. How is zakāh paid on the yield?
All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.
If the yield reaches the niṣāb (the minimum threshold for zakāh to become obligatory) — which is five awsuq (plural of wasq), equivalent to (611) kg — then zakāh becomes obligatory upon it, at a rate of one-tenth ('ushr) if irrigated by rainwater (i.e., naturally, without the use of machinery), or one-twentieth (half of the 'ushr) if irrigated using machinery/equipment.
If the yield of dates consists of different varieties, then zakāh should be paid from each variety according to its respective proportion. If this proves difficult, it is permissible to pay from a medium-quality variety [representative of the average].
It is stated in Ḥāshiyatā Qulyūbī wa ‘Umayrah (Vol.2/P.22): "Different varieties are combined together [for the purpose of calculating the niṣāb] — such as the various types of dates, the various types of raisins, and so on — and zakāh is paid from each type according to its respective proportion. However, if this becomes difficult due to the large number of varieties and the small quantity of each individual type, then zakāh should be paid from a medium-quality variety among them — neither the best nor the worst — out of consideration for both sides [the giver and the poor recipient]. If one goes to the trouble of paying from each variety according to its proportion, this is also permissible." And Allah, the Exalted, knows best.
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.
What should one who doubts the validity of his ablution and performs it frequently do?
Whoever doubts the validity of his ablution after finishing it, his ablution is valid. This is because the default is the validity of the ablution, and because doubt after finishing an act of worship doesn`t affect its validity. And Allah the Almighty knows best.