Is washing both openings (Istinjaa`) a must before every ablution?
Washing the front and back openings (Istinjaa`) is a must in case they have an impurity, but if they do not, there is no need for that, and Istinjaa` is not a condition for the validity of ablution.
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 a Christian man to embrace Islam in secret and is it permissible for a Muslim woman to marry him?
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.
His embracing Islam in secret is between him and Allah; however, it isn`t permissible for a Muslim woman to marry him except after he declares his Islam and it is ascertained that he is sincere about that. And Allah The Almighty Knows Best.
My maternal aunt`s son is living abroad; however, both our families have recited Al-Fatehah declaring our engagement. We have been engaged for three months, but the marriage contract wasn`t concluded because he couldn`t come to Jordan since my mother and brothers are abroad. Is it allowed that he sees my picture without Hijab knowing that the marriage contract will be concluded at the first opportunity?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon Prophet Mohammad and upon all his family and companions.
Betrothal is a promise to marry, so your betrothed is a stranger to you and isn`t permitted to look at you even through a picture. Once your marriage contract is concluded, you become husband and wife and he can look at you as much as he wants. Moreover, he may deputize his father to carry out the procedures of the marriage on his behalf. And Allah The Almighty Knows Best.