Pure and Impure Items

Q: I am from India. Mufti sahab please let me know that can I use liquid stiffener (revive) in our clothes for praying namaz?

Q: Is it haraam to wear pigskin?

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?