Good questions.

1. You’re not supposed to control the scenes. Instead, you’re supposed to control the views. You can use VStack to display views vertically, and HStack to display view horizontally. Then, wrap the main view (the view that contains the child views) in the WindowGroup.

Left: VStack, Right: HStack

2. I think you’re mixing up scenes with views. Switching from one scene from another is automatically managed, and all you have to use is SceneStorage. (This is basically a way to store the individual state of each scene, for example, the selected tab in a tab bar application.) See App essentials in SwiftUI at 10:56.

3 (a). This is also managed automatically, in response to a user gesture or clicking a menu item.

3 (b). WindowGroup manages all the scenes for you. Yes, it is a set of views, but it does everything automatically (for example, providing multiple-window functionality for iPadOS).

4. Just go with the flow. WindowGroup does everything automatically for you. You can check out these links for more information.

Apple Developer Documentation

Apple Developer Documentation

Thanks for the comment!