Should a person feel pleased, or have a virtuous vision after offering Istikhara (guidance prayer) in order to do what he/she had offered it for?

The result of the Istikhaarah is not necessarily that a person sees something (in his dream), or feels pleased, but the most important result of the Istikhaarah is whether a person is enabled to do a given matter or not.

Is it permissible to offer one Rak`ah in Witr prayer?

The minimum of Witr (An odd number prayer performed between Isha`a and Fajr) prayer is one Rak`ah, and the maximum is eleven, but the minimum of its complete form is three, and it is permissible to offer one only.

I`m getting old and haven`t got married yet. I love wearing the veil, but people advised me to take it off because it could stand in the way of my marriage, and that I should wear it after getting married, what should I do?

The veil (face drape) is the wear of the Prophet`s (PBUH) wives and righteous female companions (May Allah be pleased with them) and whoever imitates a certain group of people shall receive the same reward or punishment like themselves. Only those who are religiously poor deny women wearing the veil, and thinking that it stops a woman from getting married is from the evil suggestions of the devil.

What is the ruling on staring at the Holy Ka'abah?

All perfecy praise be to Allah, The Lord of The Worlds and may His Peace and Blessings be upon our Prophet Muhammad and upon all of his family and companions.

Staring/looking at the Holy Ka'abah is an act of worship even if this took place while performing a prayer, since Al-Baihaqee stated that the Prophet (PBUH) said: " Staring at the Holy Ka'abah is an act of devotion." [Sho'aab Al-Imaan]. And Allah Knows Best.