Wudhu With Nail Polish On One's Nails

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?

Azaan at the Grave Site

Q: I am reading a book called "Death The Final Journey" by Muhammad Abd Al -Mannan. In this book he states that its Sunnat to give Azaan at the grave site quoting Abu Hurairah (Radiyallahu Anhu) in Muslim and Buhkari Sherif. Further he states that in Durre Muktar its sunnat to give Azaan at the grave with it's blessings the Shaytan will run?

Fund Raising Competition

Q: A competition is being run where a certain amount is given as a donation and the donor is entered into a draw for an Umrah ticket and a quad bike. The money is used for a campaign to free a prisoner and the prizes are sponsored by third parties. Is this type of competition permissible?

Masah On a Plaster

Q: If I get cut on my finger, which needs to be washed for wudhu, and I put a plaster on my finger can I just make masah on that plaster? And do I need to make a new wudhu for every Salaah?