Sitting on a chair and performing Salaah due to back pain

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.

Sincere tawbah

Q: I have a friend who entered an unlawful relationship about 7 months ago. She ended the relationship after two months due to the guilt. She feels very impure and cries a lot about her sin. She claims to believe in Allah's forgiveness, but is unable to bear herself. She breaks down a lot and feels like she is no longer a good and pure woman. She also feels like it is wrong to put it behind her. Is it possible that Allah has wiped away her sin and purified her?

Method of giving up watching TV

Q: My parents have always guided me away from certain sins and I would say that they are Islamically inclined in that they read all salaahs, abundant Quran and stay away from most sins. However, the one habit I've noticed that they seem unable to give up is their addiction to watching television. They watch Indian soapies and Hollywood/Bollywood movies till late at night. Sometimes I think they fall asleep with their TV switched on. Sometimes they will be watching a funny video or an interesting movie while I am getting something from their room and they'd tell me to come and sit down and watch with them. I have just recently begun cutting tv out of my life and as much as I want to watch as well, I feel guilty while doing so. What dua can I read so that my parents will stop watching TV and will get more hidayat? And what can I read to strengthen my willpower so that I will not get tempted to watch TV or commit any other sins?

Uneven haircut

Q: I am a boy. When I go to the barber shop, I ask him to cut my hair short on my sides and the back of my head. But I ask him to keep the front hairs relatively bigger than those at the back. Is it permissible or must all the hairs be cut equal from all sides?

Inheritance

Q: If a man passes away leaving behind his wife as his only inheritor, how would the inheritance be distributed? Would it make a difference if he also had a maternal aunt (mother's sister)?