Android Master/Detail app and the Back button.

As the title says, have a Master/Detail app. On Android, the "hardware" back button tends to just close the app and go to whatever OS screen was up when I launched it (home page, app drawer, etc.). If my Detail page has subpages, the Back button will navigate properly from a subpage back to the main Detail page. But, if I visit multiple detail pages in my app, the Back button will not "remember" the pages I've visited, and as mentioned, just always goes out of the application.

So I have two questions:

1) Should the Back button navigate amongst the visited pages within my application? Or should it behave as it does?

2) If I wanted it to navigate among the Detail pages, how would I do that in Forms? (Android docs say you have to populate the "back stack" as needed, but I don't think that's a Forms concept...)

Thanks!