Add one more DAG member Excahnge 2013

Dear All

I plan to add one more server to our DAG, Exchange 2013 SP 1. We have around 20 DBs on server with 20 diffrent HDD's attached (VM) for every single DB and its logs

I need some help to understand that do i simply need to create sam server with same HDD space and number or a diffrent size / number can be joined to th DAG.

Currently MBX server are on Windows 2012, can the new DAG member be run on Windows 2012 R2?

Apoorv Mehrotra