we are migrating from 2013sp1 to 8.5.

in our website we have two locations for disaster recovery. This means that we have two broker databases and when a content is published, it's sent to two deployers that insert the content in both databases. In Tridion, we configured two nodes inside publication target.
How we can replicate nodes in SDL Web 8.5? we understand that we have to install two deployers but we don't know if we have to install two discovery services, only one, ...

Another doubt is which services we need to install only publication process. is it enough with Deployer and Discovery or we need another one? 
We are thinking to split publication process and CIS services for webapp in two machines and we can't find in documentation which services are needed for publishing when we split it.

Thanks.