Sub-domain from a different host pointed to droplet

Hi there, I have found several related questions, but none of them help me much to solve my problem with pointing a sub-domain to Digital Ocean.

Situation:

• I have a domain name hosted with a hosting company: example.com;
• I want to have a sub-domain (test.example.com) pointed to my droplet in ways when a user access test.example.com, the browser shows my droplet content, instead of the hosting service content, without showing my IP address on the browser address bar.

My questions:

• I read that I have to change A records for the test.example.com subdomain to point to droplet IP. Is this done on the Hosting Company Control Panel?
• Since it is only a sub-domain (not a domain name), do I require to setup anything on DNS settings for my account on Digital Ocean?
• My web service is already working on Digital Ocean droplet on a specific port. When I access my droplet IP address:port, I can see the content I want. Since I am using nginx, do I have to do anything on xginx configuration in order to make this test.example.com to point to this ip address:port?

The idea is to allow user to browse the droplet content, without seeing the IP address of the droplet. They should only see test.example.com.

Hope anyone can help me

Thank you in advance

Regards

Paulo