I can answer your questions
Borax powder is what you use to preserve the hide at is 20 Mule team borax. Your question on what type of soap do you use when washing animal hair you use regular dish soap like you use to wash your dishes. Make sure that you cut all fat and blood from your hide or hides. You should stretch them out if they are animal hides. So they get better air circulation do not worry the borax will do the work for you in curing it also makes him smell better. Welcome to this site from Oregon