Translating this as 'teacher' still may sound unnnatural. In English I think we would usually substitute the teacher's name. As in, "Of course, Mr. Smith."

Depending on the situation & era of what you are translating, I have found that "sir" often substitutes nicely. Of course, "master," "teacher" and such can also be used, but "sir" tends to offer a similar flexibility that "sensei" does.

Most often used literally as "teacher", but can be used in colloquial conversation as a compliment--sincere or sarcastic--ala "right you are, professor", or "no sh$#, Sherlock."

Would need more context to be certain but this would appear to be "sir". This may very depending on the country in which the conversation is set. "Sir" would be OK for the UK. Can anyone from the US tell me how a student over there usually responds to a teacher?

Sensei is used to address someone who is respected by an individual, groups, community or society. It is an informal title. Anyone can be called Sensei if he/she earns this title.

Sensei can be someone who is a teacher by profession or doctors, scientists, polititian or any others who have greater positive impact on others.

Sensei is pronoun, therefore, used to address someone instead of his/her name.

Sensei! I have a question. (In a classroom setting)

Sensei! What is wrong with me? (At a hospital)

Sensei! We would like to ask you if you are interested in giving a speech for us. (Great achiever)

Sadao Sasaki

Is a term of respect, usually meaning teacher, master, mentor, and so on.

It is not only used in Martial Arts as a term of respect, as many Hollywood movies have made it a fairly common word in the English language.
It is also used by school children/students in Japan to address their teacher.

Forget the "born first" nonsense. In Chinese, the term after a name just means "Mister".