I see. While making this I found that if you hide the Finder sidebar and toolbar (both are options in the menu), then your scenario plays out. In a way it’s nicer than the video on my github.
Ah yes, that may be an issue. But that is solved by not installing the "window_title_changed" hook, so that the scripts only take effect when new Finder windows are opened. In that case, windows never move around. All the points you mentioned are issues with the default behaviour of Finder (e.g. when opening a new Finder window as is, you cannot predict where it will open and so it may block other elements).