Faraaidh of wudhu

Q: As nail polish nullifies wudhu, is it okay for one with onychophagia (nail biting disorder which is part of the OCD spectrum) to wear clear nail polish or bitter tasting nail polish to prevent her or himself from biting as it is damaging to the skin around the nail, cuticles, etc and puts the person at a risk of infection if they don't take steps to stop nail biting or is it still haram despite the health risk?

Q: I have on my feet a lot of half peeled off small skin pieces (probably from little fungal infections) mostly in the form of circles. Because of this the small peeled skins borders are hanging over the skin below i.e. there are two layers of skin. Is washing normally sufficient in order to make wudhu? Also sometimes, I have the same on my hand (2 or 3 or 4 very little circles). Is just washing normally enough?