Salaah on a Conveyance

Performing salaah while on the aeroplane

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?  

Performing fardh salaah in a car

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?

Performing salaah on a bus

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?