I think 1953 is the patent date. Serial number would likely reveal true date of mfg. Do not stand it up on end. Store horizontal. Check ebay to see what comparable units go for
go to a gun store. and ask the clerk for help they are experts.
Hong Kong IS part of China, but they are in many ways still treated as separate countries. Separate money, separate infrastructure systems, and so on. If you enter China from Hong Kong, you'll need a visa...and mainlanders need specific documentation...