Creative and Concrete Specifications of Visual Studio 2015

I would like to update my Visual Studio to 2015 version. I would like to know how beneficial this is for me? What are the features added in this software? What do you mean by polymorphic? What is UTF and usage of this in computer programming? What is the function of Decltype? What do you mean by PGO Instrumentation? What is new to .Net Frameworks 4.6 and how functional this to my previous version? What are the system requirements for VS 2015?
