First of all, you need to use path_tracks, not path_corners.
If you've worked out the crate dropoff, then add a path_track (not path_corner) at the location you want the dropship to go after the dropoff.
Add an output to the dropship: OnFinishedDropoff, target itself, input SetTrack with a parameter of the name of the final path_track.
I'll upload an example map to the Example map vault.
EDIT: example VMF/BSP added to example map vault