You can’t convert map types. Better to start with a clean map, I think it’s called ‘basic’.
I’m not sure about the viewport camera. It’s easier to find out about bookmarks. When you’re somewhere you want to come back to, hit CTRL1 ( or 2, 3 etc ). Later, just hitting 1, will put you back in the same spot with the same view.
Make sure you save the map after making bookmarks.