What is the ruling on having brotherly ties between a strange man and a strange woman, and is the former considered a Mahram (unmarriageable) to the latter?

Such a relation between a strange man and a strange woman is forbidden in Islam because it involves forbidding what Allah has allowed by marriage, and allowing what Allah has forbidden such as looking and the like. Such a relation doesn`t render any act lawful between them, thus they are forbidden to look at each other, have a Khulwah (seclusion), and travel together.

I see horrible dreams although I perform the prescribed prayers, what do you make of that?

All perfect 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.

Be mindful of Allah while awake and he will safeguard you from whatever evil you see while asleep. We advise you to make the pre-sleep supplications. And Allah The Almighty Knows Best.

Do certain vaginal discharges and incontinence of urine nullify ablution, and should underwear be changed?

A person afflicted with constant impurity due to urinary incontinence and vaginal discharges is obliged to make ablution for every obligatory prayer when its time is due, and after removing Najaasah (impurity), and wearing a clean diaper. He/she is obliged to pray immediately even if the impurity is being released, and he/she is obliged to remake ablution, and the aforementioned for every obligatory prayer.

What is the ruling on eating the food prepared by Christians friends knowing that their income comes from trading in alcoholic drinks?