Most of your queries are based upon parallels which are normally drawn by the people who argue on the basis of mere logic irrespective of the logic being correct or not.
Answers to your questions:
1) If that Qawwali being discussed compared Hazrat Fatima R.A with Veena Malik, is it also blasphemous for a prostitute named Ayesha or Fatima to be called by these revered names? Is that also not comparing the two?
Faran: Whenever you call a prostitute with her name (name could be same of any pious personality), do you mean to call that prostitute or are you calling that pious personality? Its just like if your father's name is Javed, so whenever you meet a person with the name Javed and you call him with his name, are you calling that person at that time or you feel that you are calling your father? Whatever is your answer to my question, consider the same to your query.
2) The Qawwali under discussion is played in many Ehl-e-Tashee Majaalis. Is it also blashpemous there?
Faran: I personally feel that it would have been better if this Qawwali is not telecasted in any manner on the TV. However, there is a religious sect as mentioned in your question, who use to sing this Sehra on their marriage ceremonies and it has a religious association with their beliefs. So, we should not question why they sing it. However, the issue at this point of time is not this Sehra instead the way it has been telecasted in the concerned morning show.
3) The so-called Sayyads of the present day, who pose to be family members of Prophet PBUH, have had thiefs, murderers, rapists etc in their family lines. Is it also not blasphemous to ehl-e-bait to call them Syed?
Faran: How it is blasphemous to call a Syed a Syed? Do you change your caste whenever you do something good or something bad? BTW here is another aspect of the respect towards Syeds. Note that, if a person is pious, people will respect him irrespective of whether he is Syed or not. While if a person is bad, he will be condemned irrespective of his tribe or association. But for Syeds, I as a Muslims, feel that we need to restrict our condemnation for a person who is Syed and doing bad habbits and leave his case to Allah and State. This is my opinion keeping in view the human feeling which every person has towards his descendants.
4) Many of qawwalis at mazaars etc compare Prophets with a given Saint, are they committing blasphemy as well?
Faran: If there is something like this, it must be considered blasphemous.
5) In the qawwali Allah Hoo, Allah Hoo, when Nusrat Fateh Ali sings,
"Jot Sassi Ke Agar Mann Mein Tumhari Jaagay
Tum Usse Tapte Huay Thal Mein Jala Dete Ho
Sohni Gar Tum Ko Mahiwal Tasawwur Kar Le
Uss Ko Biphri Hui Lehron Mein Baha Dete Ho
Khud Jo Chaaho To Sar-e-arsh Bula Kar Mehboob
Ek Hi Raat Mein Mairaaj Kara Dete Ho"
Has the poet compared Allah with Sassi and Sohni?
Is he comparing the love of God for Prophet Muhammad PBUH with that of Sassi and Punno
Is this blasphemous?
Faran: Brother, you need to improve your understanding of poetry. This is not about parallels and istead the poet is talking about the limitations which a human has to face in Ishq e Majazi. Not blasphemous at all. BTW, you also need to understand the rules for Samaa as well. (Samaa is the right word and not Qawwali). One of the basic rules of Samaa is that it should not be done in front of common people who do not have deep understanding of religion and the poetic values. Our problem is this, we have made Qawwalis a thing of consumption for every person who even does not know basics of poetry.
6) Do prostitutes, who DO get married, pray the same Nikah prayers as Prophet's family members did? Why did GOD not make a separate dua for them?
Faran: Why Allah should give a separate dua for them? Tomorrow you will ask that there should be a separate prayer and Quran for them as well? As long as a prostitute is Muslim, she has to follow all the instructions of Islam which are applicable to a common muslim.
7) Is it blasphemous to call people named Ali, Umar etc by derogatory nicknames?
Faran: In Quran & Hadith, it has been severely discouraged to call people names whatever there name is. Period.
