Is it permissible to give zakat money to a poor brother who owns an expensive house, and is it permissible to divide the zakat into monthly installments?

If your brother has a house that he lives in and it is suitable for him, and he owns a property whose rent is not sufficient for him, then he is considered indigent and eligible for zakat (definition). He is not required to sell his house or property. However, if the house is larger than his need, then he is required to sell it and move to a suitable house. Any surplus from the house's price would remove him from the description of indigence if it suffices him.