UnScramble this Word: k a l r s e s c?

Questions

What remained closed for 3000 years until Feb 1923?

Where are Eriador, Rhun, Gondor and the Bay of Belfalas?

What are ringers and jillaroos?

In which country is HoChi Minh City?

Which internal combustion engine works on the principal of a rotating triangular shaft?