Sorry, no indicators and no “return to previous magnification”.
However you could try command-mouse-wheel to zoom in and out (or command-one-finger-swipe on the magic mouse). It takes some getting used to but can be quite powerful.
Also, don’t miss CMD-F (fit project to window), CMD-E (fit selection to window), and CMD-2 (zoom “normal”)
There IS a great convenience for zooming in to fix something, then zooming out to a previous level of magnification!
The Edit menu has “Region Save” and “Region Restore.” I use Edit, Preferences, Keyboard to assign them to the w and e keys.
Then:
Select a section.
Type w.
Zoom in and fix something.
Type e, space, control-e (this has become a quick practiced motion for me).
So e restores the selection to what it was when you typed w. It does not fit the view to the selection, but ctrl-e with default key bindings does that. And I often type space between, to start playing the selection again before the view adjustment.