Various Masaail on Qadha Salaah

Q: Alhamdulillah by the mercy of Allah, I have been consistent with my salaah with Jamaat for many years, and have no qadha from the age of 17 onwards. However, before that unfortunately I used to miss most of my Salaah. 

My family wants me to go for Umrah but I don't feel it to be the right thing for me to join them, as I haven't completed my qadha salaah yet. I feel it's doesn't make sense to do that great but nafl amal when a compulsory amal is outstanding. I would feel extremely uncomfortable visiting the Kabah Shareef and Madinah, including the mubarak qabr of Nabi (sallallahu alaihi wasallam), and then conveying the durood with such major sins and unpaid debt on my shoulders. I understand that there is obviously barakah in Umrah, but there might be barakah in making qadha salaah as well (in my opinion). 

In addition, I find that my concentration and devotion to any nafl amal is weak and I always feel that I'm wasting time since I'm not prioritizing what is more important in the sight of Allah. Please advise.

Q: If you have missed salaah for years but are now unable to make them up (qadha) because you are sick, what should you do? Is seeking forgiveness enough?

Q: Do I have to makeup for salaah if it was led by a child who is not a mukallaf?

Q: I have heard that one should pray Qadha prayer in solitude so that it should not be revealed to anyone that one is praying Qadha prayer. Is this true? 

If so, then there is a problem that in a house where one does not get solitude and it is not possible in the mosque, then what should one do in such a case? 

Then can one pray Qadha prayer in front of the family members or in front of everyone in the mosque.

Q: I woke up with my alarm fajr time then I saw that there was some time for Fajr salah to end. So I decided to sleep for some time or close my eyes for some time then wakeup and pray Fajr salah but when I closed my eyes I was getting too sleepy so I said to myself and also thought that if I close my eyes or sleep for some time Fajr time will be over but my intention was to pray salah on time. So later I woke up after the time was over...

I was so sad that I woke up after the time finished. This happened for the first time with me and it was never my intention to miss the salah. After waking up after the was time over, I prayed Fajr so is my Fajr valid?

I am so worried. I was sure that if I will sleep I will wake up after Fajr time but my intention was to wake up and pray in time and I slept to get up after some minutes but unfortunately I didn't wake up. I never wanted to miss the salah.

Q: Is it permissible to pay someone to pray qaza e umri on one's own behalf or on the behalf of someone who is dead. Please answer both the scenerios

Q: How will a person put qadha salaahs in a will because the number is constantly changing as they perform them?

Q: If a male becomes baaligh by having wet dream and ghusl becomes fardh on him, but he doesn't know that in Shariat you have to perform ghusl after having a wet dream. So he keeps praying with just making wudhu and after 3-4 months of his puberty, he comes to know that ghusl becomes fardh by wet dream. So are all his prayers in these 3-4 months counted or does he have to make qadha?

While offering these prayers again will he make intention of praying qadha prayer or will he make intention of repeating the prayer (I'adah)?

Q: If a woman gets her haidh during the salaah time, and she hadn’t yet performed the salaah of the time, will qadha of that salaah become compulsory upon her?