Some answers / corrections to want I wrote before:
for 2.: there is no need to edit header search path of your IDE. If set up in the C# build script and regenerate you project file and it will be in the header search path.
to 5. theoretically its possible to enforce/ enable RTTI and C++ Exceptions (which is needed for Pocolib) with build params, but the get ignored for Mac and iOS Builds.
e.g. MyProject.build.cs:
public MyProject(TargetInfo Target)
{
PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "HTTP" });
// Enable RTTI (prop. of superclass ModuleRules defined in UnrealEngine/Engine/Source/Programs/UnrealBuildTool/System/RulesCompiler.cs )
bUseRTTI = true;
// this seems be ignored on a mac, check UnrealEngine/Engine/Source/Programs/UnrealBuildTool/Mac/MacToolChain.cs
// Enable C++ Exceptions for this module
bEnableExceptions = true;
// eventually needed as well
UEBuildConfiguration.bForceEnableExceptions = true;