Lol yes, there will be some nasty crusty yellow disgustingness, it is a pretty ugly process to go through I was embarrassed to take Rayne out for walks while I was using Nu-Stock on her. Whatever you do make sure she doesn't go on your furniture or anything cause it does like to stain!
Nope it didn't stain her fur, not sure if it will on your girl though because she's white. Rayne has allergies so she was losing patches mostly on her face and some spots on her body. She also chewed the crap out of her tail when I first was crate training her and the hair had some issues growing back properly. All in all it worked fantastic though, the only things I hated was the smell and the random stains I would find