Xamarin/Visual Studio 2017: which .net version to pick for mobile development?

Question

I just started to develop with Visual Studio 2017 / Xamarin, Target platforms are Android and iOS.

I found no reference about whether there is any dependency between

Answer 1

The framework version of the shared library doesn't in any way affect the target framework for each device, it only affects which platform you could target and what .NET classes and methods are actually available in this library.