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 to slaughter sacrificial animals in public squares and streets?
Praise be to Allah, and peace and blessings be upon our Master, the Messenger of Allah.
The slaughtering of sacrificial animals (udhiyah) should take place in locations designated for slaughter, such as abattoirs (slaughterhouses), or in sites allocated by the relevant authorities for this purpose.
It is not permissible to perform slaughtering in a random or haphazard manner—such as in public squares, on roadsides, or in front of houses—in a way that creates health hazards, causes public nuisance, or endangers public safety. And Allah Almighty knows best.
Which is better during the day in Ramadan: reciting the Quran or performing voluntary prayers?
A Muslim should establish a daily schedule for reciting the Quran in Ramadan.
Once they have completed their daily portion (known as a wird or hizb), they can engage in other acts of worship, including voluntary prayers (nawafil). Prayer itself is called "Quran", because a significant part of it involves reciting the Quran.
Allah says: "BE CONSTANT in [thy] prayer from the time when the sun has passed its zenith till the darkness of night, and [be ever mindful of its] recitation at dawn: for, behold, the recitation [of prayer] at dawn is indeed witnessed [by all that is holy]." [Al-Isra`/78]
What is the ruling on performing ablution (wudu') and ritual bathing (ghusl) with Zamzam water?
It is permissible to perform ablution and ritual bathing with Zamzam water. However, scholars disliked using it for cleaning after relieving oneself (istinja'). And Allah the Almighty knows best.