The noun Hong Kong (two words) is a proper noun: the name of a specific place.
A proper noun is always capitalized.
From is a preposition of movement.I went from Hong Kong to Tokyo.
Yes, any proper noun can be a possessive noun. Some examples:Europe's capitals...Gene's family...The Lion King's producer...Hong Kong's harbor...The Bible's authors...Mars' moons...
"Park Avenue" is a proper noun, because it is a place. Proper nouns like this should always be capitalized.
Common
It is a proper noun, because it is the name of a specific thing.
proper
Proper noun
it's a common noun. a proper noun would be Spider-Man.
Pencil proper or common noun
Proper noun or common noun
The noun cassette is a common noun.
a common noun?