Salaah of a sick person

Q:

1. Zaid at times wasn't feeling well when praying his salah so he prayed with ishaara sitting on a chair, before the salah time expired he felt better, his condition was such that he could have prayed properly with sujood etc., is it compulsory for him to repeat the salah prayed with ishaara sitting on the chair?

2 a. Zaid is able to pray properly at home with Qiyaam and sujood etc. but when praying in the masjid he doesnt feel well, he feels dizzy, will his salah be valid if he prays in the masjid sitting on a chair with Ishaara?

2 b. In the above situation is it better for Zaid to pray five times salah and Jummah salah in the masjid with Ishaara sitting on a chair or pray at home with Qiyaam and sujood etc.?

Q: A sick person who has a chest infection, phlegm comes out on regular basis, when in salah the phlegm is in the mouth and the sick person is unable to recite anything so he spits in to a utensil to clear the mouth, is the salah valid?

Q: I have a continuous pain in my back. I can perform one or two salaah standing and doing sajda on the ground but after that, the pain is so enhanced that I cannot even stand straight. I perform my salaah by sitting on a chair, is my salah is valid or not?

Q: If someone can do qawma, ruku, and sajdah, but he can not do the qa'da; how should he make the salat? Is it permissible for him to make the Salat sitting on a chair or not?

Q: An individual is paralysed from the waist downwards. He is unable to make wudhu and there is no one present to help him make wudhu. How will such a person perform his salaah?

Q: A patient in hospital is put on drips. He is unable to perform wudhu and cannot perform salaah facing the qiblah. How should he perform his salaah?

Q: I am having some trouble in reading Namaz and I want some suggestions from you. I am suffering from back pain together with sciatica and lumber disorder (pain affecting the back, hip, and leg, etc.). Owing to which I am unable to perform sajda and rukoo smoothly in the traditional way. Doctor says that it is caused by compression of a spinal nerve root in the lower back at L4 and L5 etc. by degeneration of an intervertebral disc.). So, Doctor suggested to me to avoid standing and sitting for a long time, bending/leaning of the back, squatting, lifting weight, etc. as it will lead in worsening my condition. So, in fear of Doctors advice I am using a stool/chair in offering salat. My question is, am I doing the right thing or is there any way in which I can read namaz? Please suggest ways in which I can offer my Namaz on a regular basis without having to compromise my health.

Q: What is the status of performing salaah on a chair? If a person is unable to sit on the ground, and cannot perform the sajdahs on the ground, can he sit on a chair and perform salaah with gestures? 

Q: During pregnancy I vomit a lot. It makes my Salaah late. Whenever I make wudhu normally, I vomit and I have to take rest and make wudhu again. My question is after vomiting my wudhu breaks? In normal circumstances I know it breaks but what about these continuous vomitings of pregnancy. I don't miss my salaah but this feeling prevails that I am getting late for it. Kindly guide.