When the civilian operator asked for his location,
it generally includes two things :
a) street name
b) number on the nearest house
Are we grasping at straws yet ?
This was actually mentioned by GZ in the video walkthrough. He said that they were walking behind the houses, and there are no numbers there. (And indeed there weren't any, as anyone could see in the video.) GZ had to go to the nearest street - which was 50 yards away at most - to get to a street-facing wall and see the number.
The writer also says this:
why did Zimmerman leave his car in the first place to go after his son?
GZ was a free man at that time, and he could leave his car anywhere he pleases, and go anywhere he wants - as long as it is not otherwise illegal. There is nothing illegal about him walking on sidewalk behind houses. It was also perfectly legal for TM, by the way.
But was it wise? That's a different question, not unlike "is it wise to go to Normandy in 1944 to fight Nazis?" Of course it isn't wise, if you know what is good for you. It is patently unwise to go to war, to work as a police officer or a firefighter, to be a taxi driver, or even a thug... it is unwise to do anything that does not guarantee your safety. Still, people do unwise things because they have to. If a soldier doesn't fight the enemy, the enemy comes and kills him at home. If a police officer does not arrest the killer, the killer will eventually kill everyone in town. GZ was protecting his home because he wanted to do good. As we know, no good deed goes unpunished.