I do 3 to 4 marathon a year and enjoy that every time. Even if it's very hard.
I have watched a few marathons on television, I myself have never partook in one. I can only imagine how had it must be.
Yes it is. Especially when we come near the end
I am sure there are a great deal of marathons every year, 800 or more of all different lengths. I would also think different skill levels as well such as recreational athletes to full time experts.
Yes. To get to finish one it takes a lot of preparation. Starting with recreational is perfect.
I believe that the marathon was an original olympic event in the late 1800's with the distance to follow suit in the early 1900's. 
That is true. In Athen in 1896 and also in Paris in 1900. 
I also think that the marathon fall under the umbrella of the track and field events. Such events included jumping and running and throwing all of which would help condition for the long distance runner.