At the end of the month I am taking for a second time the 70-410 test. Most of the questions were directed towards Powershell. I am watching the Virtual Academy videos from Microsoft. They are good. I also have the Windows Server 2012 Inside Out book (not R2 I know). I would like to know if this is enough to understand PS in regards to administrating Server 2012 R2.
To be honest with you, just learn PowerShell. Learn it for your career and then you'll have no trouble passing whatever PowerShell questions they throw at you on a certification test. I wrote a blog about "IT Pro's are in for a Rude PowerShell Awakening When Upgrading Their Certifications to Windows Server 2012" back when I was upgrading my certifications to 2012 and I gave some specific thoughts in that blog article about what I considered to be the prerequisites for the 70-417 book that I used as a study guide. 70-417 encompasses the test you're taking as well as two others that you'll probably be looking to take at some point in the future.