To know more about insurance brokers, I suggest you to go through the websites of the two regulatory bodies of authorized insurance bokers in Hong Kong. They are:
1. Professional Insurance Brokers Association (PIBA)
http://www.piba.org.hk/
2. The Confederation of Insurance Brokers (CIB)
http://www.hkcib.org/
My short answers to your questions are:
1. You can find their names at the registers of PIBA and CIB (with exception of those registered with OCI.
2. Appointing brokers are not always about discounts in premium. More importantly, it is the services they render.
3. Choosing brokers or not is not a question of pros and cons. Your choice is easy to make when you understand who they are.
a) Brokers are your agent. They act for you and then seek quotations from various insurance companies. They have the duty to advise you. They receive brokerage from insurers.
b) Agents are acting for insurance companies.An agent/ agency can only represent up to four insurance companies. They receive commission from insurers.
Good luck.