For travelers, tourists and expats, Hong Kong is one of the safest places in the world. ... However, no place in the world can be 100% safe and Hong Kong is no fairy-tale land. To assure your personal safety in Hong Kong, you have to use some common sense to avoid becoming the victim of a petty crime.
https://www.internations.org/hong-kong-expats/guide/.../safety-in-hong-kong-15896

Hong Kong is The most expensive to city to live in the world as an expat. 
Average cost of food – While Hong Kong is generally expensive, there are plenty of options for cheap food. Market food, noodles, and dumplings will cost around 50 HKD per meal. ...
There are many Indian restaurants around major tourist areas. Pure vegetarian food is also available, but in limited number of restaurants only.

Transportation costs – A tourist travel pass costs 65 HKD per day and covers unlimited travel on the metro, tram, and light rail service.

Housing in Hong Kong can range from HK$10K for a small flat to HK$80K and more for large houses. The average cost of renting a typical 450 sq ft flat is around HK$15,900 per month.

Education in general and primary/secondary schools specifically are one of the other highest expenses in HK.

Hong Kong Travel Guide: What to See, Do, Costs, & Ways to Save
https://www.nomadicmatt.com/travel-guides/china-travel-tips/hong-kong/

HK Dollars. Its exchange rate is pegged to US Dollar rates. One USD converts to about 7.7 HKD. 

A mid-level job in banking, can pay around HK$40,000 per month. These amounts are subject to change, of course, and will depend on the employer.