Hello, Manik. The sentence is correct but it doesn't sound natural. Hopefully, most people know who Mr. Khan is. It sounds more natural to say "This is our Headmaster's home" or "This home belongs to our Headmaster, Mr. Khan".

Yes. :)

Good day. Yes, it is.

If you are passing it in a car or bike, it makes perfect sense

It doesn’t not sound natural. Rather say: “This is the home of our headmaster, Mr Khan.”