If the individual's title within the dept is "Assistant Professor," it is appropriate to refer to them as "Professor" in speech or "Dear Professor" in a letter.
Professor xxx is always a safe bet. If he has a PhD, Doctor xxx is also good, and Sir is always appropriate.
Dear Professor Last name.
In some circles the traditional form "Professor and Mrs David Wilkinson" is acceptable; but social change has made "Professor David and Mrs Mary Wilkinson" the widely preferred form.
Doctor.
I believe the correct address is 'Your Worship'.
Lahore
No. College is a noun, also used as an adjunct or adjective (e.g. college freshmen, college professor). There is an adverb form with possible connotations, which is collegiately.
The proper salutation for a doctor is doctor or professor depending on their title. In writing the short form can be used which will be Dr. or Prof.
As Lt. Governor.
Ms. and then your last name.
"My Lord" or "Your Lordship" are both acceptable.
Mr. or Madam President.
Honorable __________ (Insert Supervisor's Name here)
Call him Dr. unless he tells you differently.