Should vowed fast be offered in consecutive days, or not?
Vowed fast should be offered in line with what was originally intended by the vow-maker, either consecutively, or not.
Is Zakah (obligatory charity) due on leased property, and how is it calculated?
Zakah isn`t due on the leased property itself, but on the saved income from that property if it reached Nissab (minimum amount liable for Zakah), and a whole lunar year had lapsed over saving it.
Is washing the private part after urinating (Istinjaa`) a condition, and is it done with water and soap, or with water only?
Istinjaa` is obligatory for removing impurity, and it can be done with toilet paper, or a stone, or water. It is preferable to do Istinjaa` first with paper, or stone, or the like, then to wash the private part with water until making sure that the impurity has been removed. Using soap is not a condition, but there is no harm in doing so provided that it is washed off with water. It is also permissible to use either water, or paper if impurity is removed by any.
I missed fasting 30 days of the obligatory fast within the last 6 years and 20 days. How do I fast? And what should I do?
Missed fasting days must be made up, and it is permissible to make them up on non-consecutive days, as continuity is not required for making up missed fasts. Additionally, expiation (Fidya) must be given: feeding one needy person for each day if the makeup is delayed for one year. If the delay extends to two years, Fidya must be given to two needy people per day, and so on. And Allah Knows Best.