My brother is settling a debt on my behalf and in return he takes 30% interest as an additional amount of the whole sum. Is this lawful or not?
This additional amount is considered prohibited interest (Riba) according to Islamic law, and it is not permissible to take it. And Allah Knows Best.
What is the ruling on having brotherly ties between a strange man and a strange woman, and is the former considered a Mahram (unmarriageable) to the latter?
Such a relation between a strange man and a strange woman is forbidden in Islam because it involves forbidding what Allah has allowed by marriage, and allowing what Allah has forbidden such as looking and the like. Such a relation doesn`t render any act lawful between them, thus they are forbidden to look at each other, have a Khulwah (seclusion), and travel together.
What is the ruling of Sharia on marrying a Jewish woman, dealing with the Jews, and going to Israel?
All perfect praise be to Allah the Lord of the Worlds. May Allah`s peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
It is allowed for a Muslim to marry a Jewish or a Christian woman provided that this doesn`t affect his religion. As for dealing with the Jews who are outside Palestine, it is the same as dealing with the Christians; it is permissible as long as it doesn`t harm Islam. As for dealing with the Jews who are inside Palestine, the ruling differs depending on the persons themselves and the situations. By the end of the day, a believer`s heart leads him/her to what is good. And Allah The Almighty Knows Best.
Is it permissible to perform Tayammum for a month due to a medical condition that requires avoiding water?
Tayammum is permissible so long as the above excuse lasts. And Allah Knows Best.