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.
What is the ruling on loudly sending prayers on the Prophet (PBUH ) after the call for prayer Athaan?
All perfect praise be to Allah, The Lord of The Worlds Sending prayers on the Prophet after Athaan is a Sunnah for the Mou`zen (caller for prayer ) and the hearer. However, there is no harm in doing it loudly after the end of Athaan, but sometimes, it shouldn`t so that people wouldn`t think that it is an integral part of the Athaan. And Allah Knows Best.
Is it permissible to listen to chants praising the Prophet if accompanied by musical instruments?
If singing, or chanting in praise of the Prophet was accompanied by a forbidden musical instrument, then it is forbidden.
Is committing Zina (Adultery and extramarital sex) without the intention of getting pregnant or deflowered considered full Zina?
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.
The Messenger of Allah (PBUH) says: "The eyes commit fornication, the hands, the feet, and the private parts." [Musnad Ahmad, P.3912]. Sheikh Shu`aib `Arn`oot graded this Hadith as sound. What you are asking about is far graver. Generally speaking, sincere repentance erases sins, good deeds erase bad deeds, and fearing Allah stops one from committing this heinous act. In addition, the devil is man`s worst enemy and whoever surrenders themselves to the wolf will be eaten. And Allah The Almighty Knows Best.