If the breath spray is used and none of it reaches the throat, there is nothing wrong with it while fasting.

There is nothing wrong with using nasal sprays that contain that percentage of alcohol. Using nasal sprays for allergies does not invalidate the fast whether they are administered through the nose or through the mouth.

Brushing teeth while fasting will not break the fast. So, you can brush your teeth using toothpaste while fasting so long as you are careful to avoid swallowing any of it.

There is nothing wrong with you taking insulin during the day for the purpose of medical treatment, and you do not have to make up for those fasts.

There is nothing wrong with the fasting person using ear drops and eye drops, and his fast is not invalidated by that.

There is nothing wrong with congratulating one another at the beginning of the month of Ramadan. There is nothing wrong with saying Ramadan Mubarak.

Local anaesthetic does not break the fast, because it is not food or drink, and is not equivalent to them. If it is a general anaesthetic that leads to unconsciousness that lasts all day, then the fast must be made up.