Should missed Sunnah prayer be made up?
Making up missed voluntary acts of worship is from Sunnah.
Is it permissible for a man to marry up to four wives (polygamy in Islam) for pleasure although he can`t afford that?
It is desirable for the man to have one wife if there was no need for him to have more, if he can't afford marriage forthcoming expenses.
What husband's stand should be, if his wife disagrees with his mother?
Both the mother and the wife have rights on you (Questioner); therefore, you are obliged to treat both justly, resort to wisdom to please both and intiate reestablishing cordial relations among them. And Allah Knows Best.
Is it permissible for a woman to use a contraceptive without telling her husband although he wants to have as many children as possible and she can`t care for them?
All perfect praise be to Allah, the Lord of the Worlds, may His Blessings and Peace be upon our Prophet Mohammad and upon all his family and companions.
If the pregnancy is harmful to the woman, it is permissible for her to use a contraceptive; however, this has to be backed by a medical report from a God-fearing doctor. In addition, you had better inform your of what you are doing to avoid dispute. And Allah The Almighty Knows Best.