Windows Server 2012 Default RAM allocation policy
Solution 1:
Windows Server Resource Manager is depreciated in Windows Server 2012. Microsoft recommends using Hyper-V to replace its functionality (presumably with things like VM prioritization and host reserve) but this is admittedly a poor replacement. See Windows Server 2012 R2 Windows System Resource Manager Replacement? for details.
As for Window's memory allocation policy you should probably start with Mark Russinovich's series of blog posts Pushing the Limits of Windows: Physical Memory.
I believe there is no way to dedicate a set amount of RAM to a particular process anymore unless the feature is built into the application (e.g., MS SQL, IIS Application Pools).