Does not show in my cockpit. Not sure if that depends on ship or settings.
In the Phantom I am able to see it on the hull that is just outside up to the left and right. But not always that obvious and visible though.
Still, it is only a minor thing that could be useful.
That'd be good, but I think the particular HUD area for that would be around the RADAR area, rather than up the top by the clock.
And to be quite fair, there *IS* a reverse thrust indication, in that the thrust area changes so that the throttle position bar starts at the top (front) and moves down (toward you) as you increase, when in reverse. That said, it could quite easily be made a lot more obvious.