I have a few questions regarding chemical changes in products for both skincare and consumption.

1) In skincare products like lotion, if the ingredients are derived from najis sources like pork and cow and certain fish, do the ingredients remain najis or have they been chemically altered? Meaning can I leave them on my skin during salah? Also, if it does go through a chemical change how were you able to know? What proof did you get that convinced you?

2) Same question for gelatin from any source, can you eat it?

3) Does mascara and halal wudhu friendly nail polish create a barrier for wudhu? Must they be removed? As well as tinted moisturizer or foundation? As well as the mascara and nail polish for wudhu, do you accept it as valid and why?