I have a long path object that I designed in top down view but I want to have a downward slope over the whole thing. Is there a quick way I could do this? Like position my first and last points where I want them on the Z axis and interpolate all other points along the curve?
To change the slope of your curve, without changing the projected view in top view, you can use the proportional editing tool with a linear falloff in projected mode. You can find it in the top middle of the viewport. Use these settings:
Select the vertex or vertices on the far end of the curve that should be at the bottom of the slope:
Go to the side view, hit G to move, Z to move along the Z-axis and use the scroll wheel to adjust the area that is affected by the proportional editing tool. It is a grey circle around the pivot point. Try to get the circle as close to the highest part of the slope as possible without having those vertices inside the circle:
Place the slope however you like and hit enter to confirm.