About your 2, I fear that it will not be so simple. I believe that the files are modified (something with the version number added to them) during the copy in the folder…
I’m not sure…
I will check this 
EDIT :
In the NeoFurComputeShader.usf file copied in the engine directory, I found this line :
#define NEOFUR_UE4_ENGINE_MINOR_VERSION 17
Witch is not in the original file (the one in the plugin shaders folder)…
But we could make this change during the copy of the files from NeoFur/Shaders to NeoFur/Shaders/Private
We just have to find an equivalent of this
FString ShaderDir = FPlatformProcess::ShaderDir();
ShaderDir = ShaderDir + "/Private/"; // 4.17 - while the check of the shader file, look in Engine/Shader/Private
in the InstallCheck.cpp file and make ShaderDir point to the Shader/Private folder of the plugin and it will make the same things but in the right folder…
Then, we will probably have to change the 2 IMPLEMENT line to get the shader files…
EDIT 2 : After further test in editor, we’ve got another problem…
The NeoFur_compression BP has a compile error. I didn’t open it yet to check if it is serious…