looking at you main points
Dylibs need to be inside your app bundle in the Frameworks folder.
No they do not they can go in a common place like /Library/Frameworks. If there they can be used by more than one application
They need to be linked into your project via the build settings in XCode.
Yes
Dylibs helps reduce the size of the app compared to static libraries.
That is not what the document says. It says
Using dynamic libraries instead of static libraries reduces the executable file size of an app.
Thus the size of the executable file (not application bundle) is reduced. If you have put a dynamic libary in /Library/Frameworks or similar then share it between two applications then the overal size on the disk of those apps will be less than if you had used static libraries.
In general if you are releasing via the AppStore or similar and just run the .app and have no sub processes then there is no size benefit but you still get the other benefits of delay loading etc. If however you do run a subprocess from the main app then you can share code in the dynamic library, saving memory space as well as explained in Apple's document.
If you install via an installer you can place the Frameworks where that can be shared amd used by other apps. e.g. If you have two apps and they have common code you can put that in a shared place.