PCL with XS on Mac

I keep seeing lots of talk in the Xamarin blog about true PCL support, but I have yet to be successful with it on a Mac running the latest stable version of XS and stuff. A lot of the forum posts talk about manually installing the MDK. If that is required, how am I supposed to know that? Looking at the Requirements section of the doc: http://docs.xamarin.com/guides/cross-platform/application_fundamentals/pcl/introduction_to_portable_class_libraries/ does not mention it at all.

1. How do I tell if I have the MRE installed or the MDK installed?
2. I do not have a .NETSubset folder in the xbuild-frameworks directory
3. When I create a brand new PCL project, my options show the old Mono for Android and MonoTouch instead of Xamarin.Android and Xamarin.iOS
4. Should I uninstall everything or reinstall from the xamarin installer? if so, how do I uninstall everything?

Please help.