I googled your question and found some possible answers to at least one of your questions.
Why Were Early Cars Right-Hand Drive?
Historians have yet to agree on why control of an automobiles steering switched from right to left but I have my theories.
To begin with, a horse-drawn wagon was always driven on the right side because the teamster could always hold the reins with his left hand while pulling on the brake with his strongest arm. Some wagons used a foot brake directly on the wheel but that too, required a person’s strongest side. Many, but not all cars, continued this tradition by placing the tiller in the middle of the car where it could be steered by either the right or left side of the car.
Another reason for the right hand steering was that lots of roads turned to mud in poor weather. It was far better stepping down out of the car directly on the sidewalk than in walking around the car.
I have also heard that while driving on dangerous mountain roads, drivers wanted to see how close they were getting to the edge.
In any case, premium manufacturers thought it crude to place the gear shift and emergency brake in the middle of the car where they would be in the way of the passengers.
It is likely that the switch to left-hand steering was accelerated by the rapid increase in the number of automobiles. Poor drivers worried about passing on-coming traffic on the narrow roads of the day.
Why Henry moved to left-hand steering when he started producing the Model T Ford in late 1908 is generally thought to be because it was cheaper but that seems unlikely since all controls were still just as far from the center of the car.
On the other hand, the move from right to left-hand drive saved most other companies a bundle since it eliminated a whole lot of linkage to the transmission and provided a strong foundation for the emergency brake. The move also provided access to the emergency brake to all riding in the front seat
The last American cars to switch were Pierce-Arrow in 1920 and Stutz the following year although Stutz did offer right-hand steering on some 1921 & ‘22 models.
I would like to have a right hand vehicle, just for the uniqueness if nothing else. It can have some advantages especially in a city.
Trying to visualize why switching to left hand drive " eliminated a whole lot of linkage to the transmission and provided a strong foundation for the emergency brake" and it doesn't make any sense. What difference would it make?
I was interested to observe that the steering wheels of all the automobiles prior to 1928 were on the right side and the steering wheel on every automobile after that time was placed on the left side. It was as if someone had passed a law. I inquired of the staff and they had no idea what I was talking. Subsequent cursory research into the Internet has also been unavailing. Do you have an insight into the obvious question, why?