Does touching women temporarily forbidden in marriage nullify ablution?
It is prohibited to touch, or to shake hands with such women as they are considered strangers, and doing so nullifies ablution.
I have asked a marriage official to conclude my marriage since I have no proxy and, being an adult, I can act as the proxy of myself, but he refused. What should I do?
All perfect praise be to Allah the Lord of the Worlds. May Allah`s peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
In order for a marriage to be valid there must be a Wali (Guardian) for the woman: father, brother, paternal uncle or any paternal relative. If there isn`t any, then the judge can act as the woman`s guardian and conclude the marriage contract. And Allah The Almighty Knows Best.
Is permissible to buy/sell with non-Muslim?
Yes buying/selling for a Muslim with non-Muslim is permissible as regards what is lawful.
What should a person, who delayed making up missed fasts of last Ramadan due to the continuance of the same excuse, do?
It is permissible for one, whose excuse for not making up missed fasts of last Ramadhaan has continued, to delay fasting until the excuse ceases to exist, and he is considered neither sinful, nor obligated to pay a ransom. And Allah Knows Best.