Salaah on a Conveyance

Q: A person read salaah on the plane. Due to severe turbulence and short time for asr and the flight crew not allowing him to stand, the asr Salaah was read sitting on the seat not facing qiblah. 

I understand that one will have to repeat this salaah standing up afterwards. The time of asr ended and maghrib time came in. The flight now landed. 

1. Will the Asr Salaah be regarded as invalid and Qadha have to be read (fardh not done at all), or was it a valid adaa but necessary (waajib) to repeat the salah? 

2. If one is saahib e tarteeb and the next salaah comes (e.g. maghrib comes in), will one read the next salaah (maghrib) first, or repeat the salah in question (asr) first? 

3. If someone in the family did not have wudhu, and neither had anything to make tayammum with, then performed the Asr Salaah sitting on the seat in that state, will the masla change in both questions 1 and 2?

Q: I read in one of your fatwas that if a person is unable to pray standing in a plane and therefore prays seated, they must repeat the salah later on. Is this because 

* The first salah was invalid - so that they should intend qada when they repeat it? 

* Or was the first salah valid (i.e. fulfilled the fard) and the second one just a repetition of it in a more perfect manner?

Q: I have to travel from Dallas to Dubai, how do I calculate onboard prayer time? Flight is for 15 hours approximately.

Q: Does one need to read qadha of the salah read on a plane?

Q:

1. If I am travelling on an aeroplane, and the salaah time enters, then what is the correct way of performing salaah and what timing do I follow for each salaah?

2. If there is not enough space to perform salaah due to the aircraft being small, or the airline does not allow me to stand and perform salaah, will it suffice for me to sit in my seat and perform my fardh salaah?  

Q: A person is travelling by bus. Since the journey is lengthy, the entire salaah time will pass while he is on the bus, and the bus will not stop anywhere during that time. In this situation, how should he perform his salaah? Is it permissible for him to perform it while seated?

Q: While travelling in a car, my family prayed the obligatory namaz sitting in the car. Later I found out that sitting while being able to stand invalidates namaz. It was also raining heavily so is the prayer valid as it was done out of ignorance or should I tell my family to repeat those prayers?

If they have to repeat it, should it be prayed as qasr?

Q: Can a muqeem read his sunnat muakkadah salaah in a vehicle, on the highway?

Q: Kindly advise options for a pilot to perform salaah whilst on duty.

Q: I am an employee in india. The maghrib time in summer (which is the season right now) starts at/after the time when my office bus starts (6:30pm) to drop the employees. Since I take the office bus and my home is approximately 2hrs, my maghrib takes place in the bus whilst being seated. There is very little khushoo with everyone staring at me and it is troubling me a lot. Is it valid for me to join my maghrib prayer with asr so that I can pray it peacefully in office before starting? If valid, can I join asr and maghrib until the sunset time changes to before 6:30pm which might take 4-5 months?