How is scallability and reliability provided to microservices?

Good afternoon,

I’m getting into microservices – in fact, I’ve managed to make few full projects based on that architecture – but they weren’t really robust, so I couldn’t get the full scope of using microservices.

I’m struggling with 2 concepts related to scalability and reliability, and I would appreciate a simple explanation in layman’s terms.

1. Reliability
   Let’s say that I have Docker and utilize it to run 3 instances of the same image (service).
   They can’t all be bound to the same port, so the generated ports are usually n+1 (9000, 9001, 9002) – do I have to implement a service discovery that checks whether one of 3 ports is available for usage – or does Docker have something implemented that’ll allow me to define a single port (9000) that’ll redirect traffic to a service instance that is available and has the lowest load?

2. Scalability
   Let’s say that I have 3 different services: Apples, Oranges, and Bananas.
   Now, let’s say that Oranges are used the most and need to be scaled by adding a few instances but on a different server.
   How does that process work? Do I just create instances on a different server? But then what – how do they get connected to the other services?

Thanks for your time!