I was expecting too use backspace to delete a track segment and the mouse wheel to raise / lower the track; also right mouse button to cam rotate.
With regards to gameplay I think the track editor should encourage making fun to play tracks rather than any tracks so if you have figured out what makes a track flow or fun then make it easy to create such tracks (smoothing option comes to mind to take out the sharper turns).
Looks really great and reminds me of Stunts from back in the day where I spent hours swapping tracks on floppies!