I confirm. When I was younger it took one month to process a work permit and police loved to come at the working places during that period to catch foreigners. Don't ask me who told the police that a work permit was under process for that particular place, but no doubt they shared the money Farangs gave to the police to avoid arrest.
Hong Kong is in China, but has a separate passport with different travelling rules.
It was rented to the British for 100 years and given back to the landlord at the end of the lease, no acquisition needed then. The fact that the landlord had changed his political system in between is another story.