I want to buy a house by having a loan from a bank?
If taking a loan from usrious banks it is impermissible; on the other hand, if this took place through Islamic ones then it is permissible to get the loan, since Allah the Most Exalted Said (What means): "And Allah has made buying lawful and forbidden usury (riba)." And Allah Knows Best.
What is the ruling of Sharia when husband kicks the wife out of his house without a lawful excuse? Moreover, in such case, when she stays at her parents's house for several months, is she allowed to claim maintenance through a Sharia court?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
It isn`t permissible to kick wife out of house save for a valid reason since Almighty Allah Says (What means): "O ye who believe! Ye are forbidden to inherit women against their will. Nor should ye treat them with harshness, that ye may Take away part of the dower ye have given them,-except where they have been guilty of open lewdness; on the contrary live with them on a footing of kindness and equity. If ye take a dislike to them it may be that ye dislike a thing, and God brings about through it a great deal of good." [An-Nisa`/19]. In addition, it is the duty of the husband to provide for his wife and children in kindness, and this includes food, garment and residence. Moreover, dialogue and supplication are the best means for solving marital problems; however, the wronged party may resort to court. And Allah The Almighty Knows Best.
Is permissible to buy/sell with non-Muslim?
Yes buying/selling for a Muslim with non-Muslim is permissible as regards what is lawful.
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.