Tahaarat

Q: My dad has a pair of relatively old brown leather slippers. As I am not an expert, I do not know if any part of the slippers is made from cow or pig leather. Yesterday he used those slippers for wudhu and with wet feet, he walked in a carpeted room for Salaah. I then performed wudhu in a separate pair of slippers and walked in to the same room, with wet feet, to perform Salaah in Jamaat with him. Some wetness that remained on my feet, transferred to my clothes whilst in the sitting position. My dry hands touched the same carpet. Questions are as follows:

Q: Minuscule food parts in mouth after wudhu, does it affect the wudhu from being valid? i.e. they were floating in the mouth when rinsing mouth during wudhu. Moreover, what is the ruling on doing wudhu when one has food particles between one’s teeth?

Q: After wudhu and prayer one sees few (say 3 or 4) black minuscule grains of something (like a minuscule grain of powder or dust) under the nails, had it affect his 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: Somebody takes ghusal (including wudhu), afterwards he put on his khuffayn. Later on he discovers a part that he left dry (such as his belly button) during ghusal. Must he also take of his khuffayn and wash the feet together with the part he left dry?

Q: I want to know the ruling of using automatic washing machine. Is our clothes pure or impure.

Q: I had a cut on my knee and it bleeds, then I put a plaster on it. When I make wudhu then do I need to make a new wudhu for all namaaz?

Q: If the clothing of a person, or a part of his bare body (such as his hand) or his khuff, touches an impure place which is dry, does it make it impure? For example, there was some urine on the carpet, and then it dried totally. If the above-mentioned things touch it, do they become impure?

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?

Q: After brushing my teeth with a Miswaak, my gums bleed. How or until when, do I have to complete my wudhu thereafter?