How long after the Ford Model-T debuted did it take for someone to wreck it? Was it treated like any other traffic accident at the time? At some point, did the laws for automobile accidents change drastically from the laws regarding carriage accidents and the like?
How is the Model T the first automobile? Commonly Carl Benz' Patent-Motorwagen Nummer 1 is considered to be the first automobile in the modern sense, but there were inventors long before him who built vehicles that moved under their own power. In 1769 Nicholas Joseph Cugnot built a steam powered vehicle for the French war ministry which can be seen as the first automobile. Since he drove the prototype against a wall during trials he also gets the honor of causing the first automobile accident.
I can't answer the second part of your question but the first automobile accident is said to have occurred in 1891 in Ohio City, Ohio. source: Ohio History Central