While it may be expensive, if you wanted a simulation that was geared more towards testing the physics of track layouts instead of trying to animate a coaster you could probably attach 3 collision rays shooting downwards from the vehicle- two on each of the front corners and 1 in the center of the back side. These can act as sensors to see if the car is on the track. Using this setup you could see if the coaster is turning (using the front two rays) or changing its pitch (using the average z position of the front 2 rays and the z position of the back ray). Based on the information you receive you can adjust the HPR of the car accordingly. Hopefully that helps you out with your first question.
Once you know the car’s angle, you can then create a basic formula that adjusts the speed of the car. the CollisionHandlerGravity class may help you here.
For your second question, if you use tasks you can monitor the movement because those activate each frame. .getPos will tell you the location of your car each frame if it’s within the task, and if you want you can use it and some pretty simple calculations to get the speed and acceleration. To be honest, I don’t know what wobble is so I wouldn’t know about that.
For question 3, yes you can and it’s pretty simple once you know how to use collision surfaces. There’s a series of very useful tutorials in this thread (Panda3d Collisions made simple) that’ll help you with everything gravity and collision related if you need it. Good luck!