I often feel overwhelmed by so much guides and frame edges in inDesign. Is there a shortcut to show/hide all of these in order to get some immediate glimpse of the final result?
Look in the view menu. Toward the bottom you will notice a lot of the entries start with "Show" or "Hide", there are most of your active view extras. Also see in the extras menu within view, that is where the content grabber (my least favorite extra) and others. Pressing W for preview to clean a layout up briefly is also a quick toggle option as stated above.
W hides all guides and frame edges, but it does not change rendering mode - if you didn't change that in settings, you'll still see all media as previews only.
But pressing shift+w enters you into presentation mode, which besides hiding all interface elements and hiding all guides and frame edges, also renders all media in high quality. Presing it again returns you back to edit mode.
Also to only hide guides and margins, you can use the cmd+; (or ctrl+; in windows) shortcut.