Impurities

Q: If a root of a hair falls in ماء قليل (little water), does it become najis?

Q: Sometimes I notice a stain (white, mazi) on my pants but I don't know when it came out of my private part. I don't know if I need to repeat the previous salaat or not? What should I do in this situation?

Q: After intercourse with ones spouse, is it necessary to wash all the bedding and linen? Or just the spot that's messed? Also after one performs ghusl , semen comes out, is it necessary to repeat ghusl?

Q: Is it jaaiz and permissible to use donkey milk soap for washing face and hands? Please advise on that.

Q: Does getting urine on one's body require that person to perform ghusl? Because in old age sometimes one gets a few droplets of urine on oneself
without knowing, what should one do in that case?

Q: I wanted to find out if precum is napaak? Do I have to change my underwear everytime I get precum?

Q: Is the root of a hair Taahir or Najis?

Q: 

1. I am over conscious about purity and cleanliness. Even though I do my best to wear clean clothes, have clean body and wudu properly so I can offer salah perfectly but I always have doubt about cleanliness. I feel if I touch most things I'll get germs I have to repeat my wudu again. I can't able to do wudu any place anywhere I worry about cleanliness of the place. I have 3 different clothes, I wear 1 set of clothes for toliet, I have 1 set of clothes for going out and I have 1 set of clothes for praying salah.  I worry that if I wear same clothes that I went to toliet with that clothes wouldn't be clean for salah.  I wear sandals at home because I don't want to get germs or dirt from carpet.  I try to avoid touching the door handles so I don't want to get infected with germs. I get thoughts  place where I pray it's not clean enough. If some else prays on my praying mat (carpet) I feel that person made my mat dirty I have to wash it. I waste too much water and long time in wudu and ghusl. I follow the tiny things that are not even seen by eyes to clean them and remove them. After I do wudu I get thoughts like I didn't do wudu properly or I didn't wash 3 times each part of body or I have to repeat wudu again because I was bit careless when doing wudu.  These thoughts I get do I have to accept them or ignore them? I feel if I don't listen to these thoughts my prayer will not be valid?
2. How do keep yourself clean but not trying too hard or listening to shaytaan whispers?
3. I am pretty sure I am suffering waswasas with regards to cleanliness, how can I stop these thoughts?

Q: If the fat from pigs is chemically processed so as to produce two compounds, both different from the original fat, it would be considered as istihalah?

Q: What is istihaalah? Especialy regarding products from pig?