You have asked several excellent questions.
The car’s stability is a matter of careful programming and many sensors. It is programmed to move very smoothly, as if a very conscientious chauffeur were trying to impress you.
With the destination selected, the entire trip is anticipated, including the necessity of slowing slightly to mix in with other spherical elevator cars, on their appointed rounds. Each twist and turn is anticipated, and the car adjusts smoothly to prepare for them. Just as a roller-coaster banks into hairpin turns, the spherical elevator cars rotate and tilt to accommodate the gentle accelerations. You hardly know you’re moving.
But there are seats available, and most people choose to take a seat after entering and selecting their destination. The car can sense how many people there are, and adjusts its forces to match.
There is no fare, per se. Excessive usage, or business usage, as for making deliveries, is billed out on a monthly account, rather like a cable services bill. If you use more services, you are charged more. The fees are moderate, as the cost of maintenance and construction are the lion’s share of what such a system will cost a community.
If you have and carry a cell phone, there are applications to link you to the transportation system, to enable you to use it more efficiently and plan your trips with precision.
The system extends as far as it is practicable to do. That would include city centers, parking garages, venues, restaurants and municipal buildings. It is advantageous for office buildings and manufacturers to be a part of the system, and they are expected to contribute heavily to be able to participate.
Safety is a paramount concern. The same system of sensors that monitors the people boarding can check and display in advance whether a called car is empty. If you are concerned, you should not enter. Similarly, the sensors can display whether the area to exit into is clear of people nearby. You would not have to exit before checking for hostile presence.
It is widely circulated that any indication of a crime being committed within a car can result in having the car immediately reroute to a safety spot where trained security personnel will ascertain what the problem may be and what actions should be taken. It is advisable to teach your children to be orderly and in particular not to scream and throw tantrums while being transported.
Making criminals aware of this policy tends to reduce their willingness to enter a closed space where they cannot slip easily away.
For an “underground” type of system, it prides itself on having sunshine as the best disinfectant. By that I mean visibility.
After reading your elaboration, I feel that I was born too soon. Up to this time, I felt that I’m so lucky to see many of the fascinating changes that have been made and have occurred. The security features are top-notch! (Unlikely that anyone capable of high-end crimes would be involved in public-transportation mischief.)