Impurities

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?

Q: 

1. The splashes of water when washing our private parts in istinja is paak or napaak?
2. The water which wets our feet due to movement of our hand in these situations is pure or impure?
3. Our hand with which we have cleaned those areas if it touches our clothes will the clothes be naapak?
4. Once this happened and where I thought that my clothes has touched my hand, I washed it with water and offered namaz and after some time I began to think that i washed the wrong place. Now I don't know was my namaaz valid?
5. When we wash our hands aftr istinja and the sleeves fall down and it gets wet, do we have to wash our sleeves or not?