Should missed Sunnah prayer be made up?
Making up missed voluntary acts of worship is from Sunnah.
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.
What is the ruling on obtaining a house through the King Abdullah II project (Decent Housing for a Decent Living), knowing that we do not own a house, our financial situation is moderate, our current rental costs are high, and we are eight people living in the household?
If owning the apartment/house is done through the same institution/project then it is permissible, but if this took place through usurious banks then it is impermissible, since dealing with usurious transactions is unlawful. And Allah Knows Best.
Does touching one's wife invalidate ablution?
Touching the wife according to the Shafi'ee's doctrine invalidate husband's ablution. And Allah Knows Best.