Qadha Salaah

Q: If I have qadha salaah to perform, can I perform it after Asr salaah?

Q: I have qadha salaah from a certain year. I have read salaah in between but I'm not sure when my haiz fell during the year as well as which salaahs I read.

My question is, my intention for the qadha should be made from a specific date that my salaah became obligatory and each date so on till the current date, or should my intention be that, from the first of all the qadha I have right up until a number I assume I missed. 

Q: Regarding qadha salaah (missed prayers):

What is the full intention to make before one performs a qadha salaah (Note: the intention for ample salaah missed not just a single salaah). I am fearful that if my intention is incorrect my qadha salaah wont be accepted. Many books have the intention for only missing one prayer. 

To my knowledge the intention is "O Allah, I am reading the 1st fajr of those that I have missed" but I am unsure if it is correct.

Q: What is the method for qadhaa namaaz and fasting?

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?