How does pitch relate to glide angle?
When you pitch the nose down to gain speed, it feels as though you are pitching down a long way

This is because the change of the cockpit angle towards the horizon is the sum of both the angle of attack and the glide path angle change.
This means that at low speed your speed changes should move the target point up when you go faster (the point is only affected by the change in glide angle while your view is affected by the sum of angle of attack and glide angle change) while at high speed, when a speed change means only very small changes in angle of attack) the target point does not move much relative to the canopy any more (but it will still move a bit up when going even faster).

How does pitch relate to the polar curve?

All you need to do is to add the angle of attack at the respective speed to the polar curve and you get the pitch angle. Like this:

The blue line is the arcsin of the ratio of sink speed to flight speed. It should not be a coincidence that it looks like the sink speed polar. To that line I added the angle of attack (red line) which shows in which direction relative to the horizon the longitudinal axis of the plane points. Since the cockpit is a bit angled down, your viewing angle should be reduced by that amount. Now it is easy to see that the angle changes a lot at the low speed end but stays almost parallel to the sink speed line at high speed. Since I assumed a zero-lift angle of attack of -2°, the red line crosses the blue one at 52 m/s.