Making salaam or saying Alhamdulillah to a sneeze when a portion of the satr area is exposed

Q: If a man is wearing shorts and his knee and a portion above his knee is exposed. Can such a person greet? As they are saying the name of Allah while their 'awrah is exposed? 

And what is the ruling regarding saying alhamdulillāh after sneezing when one is dressed in a similar manner? Is it makruh or more serious?

Performing salaah on a plane while sitting

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?