Qadha Salaah

Q:

1. I have a lot of qadha salaah and I don't know exactly how much, how should I calculate all my salaah?

2. While performing my qadha salaah, can I perform all the Fajr, then all the Zuhr, then all the Asr and so on?

Q:

1. If I am offering my qadha namaz and iqamah is called for the next prayer, do I have to stop praying qadha?

2. If I prayed full qadha namaz in this situation, is my qaza prayer valid?

3. What if I am just about to complete my qadha prayer and iqamah is called for the next prayer?

Q: I have nafil and sunnat prayers to make up that I used to break in the past and are now wajib. Is it valid if I make the niyyah of "2 rakat wajib"? Or do I have to specifically make niyyah of sunnat/nafil and which daily prayer they belonged to?

Q: I have recently heard that if you start a prayer, even if that prayer is nafil or sunnat, and you break it, that prayer becomes wajib. I used to do this quite often in the past. Can I offer tawbah or must I make them up? I have no idea how much I have, so if I must make them up, how should I go about doing so? 

Q: If one has made Hajj and and during Hajj one made sincere taubah for missing previous salaah and since Hajj one has never missed another salaah, do you still have to repay your outstanding salaah that was incurred in the years before your Hajj? I am asking because I read that the person who performs Hajj emerges sinless (all sins forgiven) like a newborn baby, and sincere taubah was made for missing previous salaah. 

Q: If one misses a salaah while travelling, are you allowed to perform qadha salaah by joining (e.g. Zuhr and Asr) and shortening the salaahs as you are still busy travelling? This will mean, for example, performing two rakaats for Zuhr and 2 rakaats for Asr in the time of Maghrib?

Q:

1. What are the conditions of a baaligha? I started having vaginal discharge at the age of 8, but only began praying and fasting at the age of 11, which is when I first got my period. Must I make up 3 years of prayers and fasts? If I had masturbated before having my first period, and do not recall excreting discharge with any coloration, was I baligh?

2. Can I make up prayers with intention of "this prayer or that"? I have some fajr prayers to make up for (I have no idea how many as I used to sometimes pray them at the time when one should not to sajdah).

3. I also have to make up 2 rakat nafl and sunnat prayers that become wajib when one breaks them, which I did often. So, when I am let's say doing maghrib prayer, for the last 2 rakats, can I make the intention of "either maghrib nafl, fajr fardh, or any wajib"?

Q: Are you allowed to read qadha salaah replacing 4 and 2 sunnah of zuhr

Q: Is qadha prayers accepted by Allah?

If I go out shopping or to a wedding, can I pray qadha when I get home and is it accepted?

Q:

1. As a youth, someone made an oath to not do something and they did it, they then fasted 3 days to expiate the oath (as they were unable to do anything else). Later that person apostatised from Islam but came back to the Deen. Do they have to redo the expiation for the oath broken? No oath was made since that time. 

2. Also, in terms of salah missed, are salahs missed over years must be made up by someone who Apostatised but later came back to the Deen?