Is it correct that everything dry is pure even if it has impurity on it?
If something impure becomes dry, it remains impure and is not purified by drying. However, the impurity does not transfer by touching it if the one touching it is also dry. And Allah the Almighty knows best.
Does the use of suppositories, enemas, or hemorrhoid creams affect the validity of fasting?
Enemas and suppositories inserted through either of the two private passages invalidate the fast. This ruling is based on the statement of Ibn Abbas (may Allah be pleased with him): "Breaking the fast occurs from what enters (the body), not from what exits." [Reported by Al-Bayhaqi in As-Sunan Al-Kubra]
His generalization regarding anything entering the body indicates that it invalidates fasting, whether it is nutritious or not, as even non-nutritious substances resemble food in form.
It is recommended to use them before Fajr or after Iftar. However, if a person must use them while fasting, they should continue refraining from food and drink for the rest of the day and make up for that day later.
Is Zakah (obligatory charity) due on land intended for selling?
Yes, lands intended for trade are valued, and Zakah is paid according to their estimated value after a lunar year had lapsed, but if the owner didn`t pay the due Zakah, then he should do so after selling them.
Is it permissible for a woman to wear underwear while performing Umrah?
Yes, it is permissible for a woman to wear underwear while performing Umrah. This is because she should keep her regular clothes that cover all her body while being in a state of Ihram (ritual consecration) for Hajj, or Umrah. However, she should uncover her face and hands, but it is permissible for her to let her head-covering garment drape from her head down over her face when non-Mahram (i.e., marriageable) men pass by her. And Allah Knows Best.