I don't think it would. Anbesol has benzocaine in it, which theoretically should cross-react with the cocaine test. The two things that are working in your favor: Anbesol contains very little benzocaine, and you use very little Anbesol. There are thresholds on drug tests, and the little bit of drug in Anbesol won't cross it.

yes

Yes, you can put anbesol on the gums after a tooth has been extracted ONLY after 72 hours. The reason for the 3 day wait is because of the blood clot. Anbesol and other oral anesthetics can cause tissue damage and inflame the tissue. If the blood clot is ruptured you will develop dry socket.

Anbesol is meant to help pain that occurs on the inside of the mouth, like tooth aches or gum pain.

It may sooth the pain but may not do much for the sores. It's best to get some cold sore cream like Abreva.

Yes, too much of any Benzocaine can cause a false positive.