This would be a huge violation of privacy. The government should only monitor suspicious individuals if they have evidence of some misbehavior that could harm other people.
A persons appearance doesn't tell you about the person itself, although a lot of people do judge by what a person is wearing. A person's clothes makes a first impression but doesnt show who the person truly is.
No, this will cause a lot of problems around the U.S. There is no reason for the government to get involved in the church. This would cause a lot of turmoil about religion around the U.S.
I think facial piecings should be allowed as long as they are a reasonable size. The big attention seeking piercing should be banned. The District should maybe make a new rule depending on the size and the position of the piercing.