Which Compiler ?

There is no restriction for your compiler as you do not execute compiled RR functions, you only access data structures in memory that are compatible between compilers.

The examples are made with Visual C++ 2013.

But the example have .pro files to use them with the Qt Creator as well.

Qt framework ?

The QT framework is NOT required to write C++ plugins.

But some SDK examples are using it.

Note: If you try to modify an example plugin to use it without Qt, you have to remove the QT precompiler definitions and library includes.

You can download the free LGPL Qt framework SDK from the Qt page.

If you want to use Visual Studio, then download "Qt libraries 4.8 for Windows (VS 20xx)"