Can you please suggest me about "Cloning your existing machine" if I installed elasticsearch in es1 and then I follow the Cloning your existing machine.It will replicate the es1 configurations es2 or not
Not sure exactly what you mean. A machine clone is identical to the original, including all the configuration residing on the machine.
and another is to how to establish communication between es1 and es2 instances while installing in production.
That's exactly what the plugin helps you with. In the example in the plugin's readme file all instances are connected to the es-cloud project and the ES instances will attempt to form a cluster with the machines in that project.