So the ghost train has a simple lock and unlock, kind of like a spinning mouse coaster. the lock mechanism centers it, making it face forward. It has lift hills and seems to speed up a little when going down hill. It will complete a full circuit if it's flat though, you do not need elevation. You can define the speed at which it moves on flat track. If you create the right curves, you might be able to spin it in a certain way in a somewhat predictable manner. (I gotta try it with guests though)
The Huntsman gives you a lot more control. It gives you yaw (spin), Roll (lean left-right) and Pitch (lean forward-back). The way you set it put is you select the position that you want for each sectiion, say you are turning the track left in a circle and you want them to look at the center the whole time, then you set your yaw to 90 in the circle; the transition will occur on it's own. If after the circle you want them to face forward again, then have one piece with yaw set to 0 so it transitions to it in the short term, (otherwise it will transition to default position over the rest of the ride or until the point at which you set your next position) Works pretty much the same as the 4D coaster.