My LFS orders stuff from every where so no idea. All their corals look great. If They notice things, they take action.
Vermitid snails can ittitate if there is enough. Only 2 I have seen but not sure as they have not sent out typical weebing yet but not to worried. They only become a nuissance when there is to many. So will keep eye and may remove next water change.
Sponges are great to have and rarely cause problems. So definetly dont want to scrub. The eggs I will probably remove next water change. The flatworms i am keeping an eye on. I dont think these are the coral eaters but possibly mucus eating. I will just need to watch. As treatment for them will also kill the featherdusters as well as other beneficial things.
Definetly cause for concern and definetly understand. My next water change is around thursday, or when elegance tells me. Since I do 100 percent changes, ill be able to look over and see what I need to do. With. Coral being at fish store for months and happy with these, i am just watchful.
Most people when they get corals automatically dip and treat to prevent things and kill bacteria. Since I am relying on my corals for bacteria, dipping would not be a good way. Now that the coral is in and been a week. Dipping can be an option if needed.
I look at what ypur saying as trying to protect things from happening.. definetly not opposed to anything you mentioned. May even come to treating.