Hi Josh,
Good questions but there is not always a good answer. I will speak of AI flight here but vehicles and ships have the same tendencies. AI flight has always been quite finicky in the sims. It is always thought of as "eye candy" because of its many limitations and eccentricities. Moving backwards at startup has always been built in to the sim and is not something an AI Developer can control. In fact, the four basic things that the AI developer controls is where to start, when to start, what airport to go to, and where to park.
The sim does most everything else including backing the AI plane up when it starts. The sim follows the runway defined by the code that created the airport and then the sim decides what route in the air the plane takes. In general it is very common, in mountainous areas for planes to take off, fly for a while and then run into a mountain. You mentioned the hard landing the Maule makes but I see many AI planes just crash.
I think the backup maneuver at start was put there to help the AI object move away from another plane, dock or other object that it might be parked behind including a building before it starts to turn. But that is just a guess.
As far as start up times, a lot depends on how the user gets to the scene. For example, did the user fly there? Did the user start the sim there etc. Normally, if you start the sim from scratch and set the time to be 30 seconds before the time the AI plane is supposed to start, the AI plane will almost always start up within 10 to 20 seconds after the set time for its start up. If you get there in another way, it can be a bit more random. And, if the AI planes is making a longer trip and you arrive in some fashion other than startup, the plane may not even be there because it is en route to its destination.
So you just sit back and enjoy the eye candy when it appears because sometimes, you never know when
Rod