It seems that both the gimbal pitch (Interpolate mode) and the altitude settings indicate what they will be at the particular waypoint and if they are different from the preceding waypoint then they will gradually made the transition over the distance between the two points. What if I want to go to a waypoint and shoot pictures from an attitude that is safe at that point but would be too low for the trip to that point? How can I fly to a point and then descend only after reaching that point, pause and then ascend again before moving on?  

  

put waypoints in between for the safe altitude ,  as many as you need.  As long as they are not too close together.  Adjust the speed to suit.

As Knee said.  You will have to zoom in close on the map to set the waypoints accurately when that close together, but it works as I have done it many times.