This story drives home several points, key among them are: everyone who ventures beyond suburbia should know the basics of survival; that rules like "don't talk to strangers" must be presented with reasonable exceptions; planning beats luck...but luck is good.
The key to Brennan's survival here was pure luck - the weather was quite warm throughout the 4 days (and nights) he was missing. Had it been just a few degrees colder, or rainy, the outcome could well have been different.
The sheriff (I think) who organized the search made a critical mistake by assuming that Brennan would follow one of the basic survival rules - that travelling downhill, and especially following water downhill will bring you to civilization. Apparently, that was a lesson that Brennan had yet to learn, but the sheriff who assumed it would be followed made (in my opinion) as serious error of judgement in assuming it would be followed. Of course, I sit here with the clear perspective of 20/20 hindsight, that was something the sheriff did not have.
One very inexpensive survival tool that can be used by almost anyone is a garbage bag (and some training is necessary for kids - they must be instructed never to put their head into the bag). It can be easily made into a raincoat by making arm and head holes. Its impervious nature means it holds heat, critical when spending an overnight in the woods (or even an inclement day). Matches and candles are also very helpful, but I don't think they are appropriate for 11 year-olds. A pocket knife might have been helpful, but again, the age factor brings it into question. The item Brennan should have been carrying was a whistle, they're cheap, can be heard over long distances and you can't do any real damage with them. Had he had a whistle, once he realized he was lost, all it would have taken would have been the advice - if you're lost, blow this whistle and stay where you are and he'd have been recovered within an hour or so. To me, putting kids into the woods without a whistle is inexcusable.
Finally, it seems like Brennan had avoided people, there seems to be a story of his hiding from people on horseback. This could have cost him his life. Kids must be instructed that in an emergency (and lost in the woods is an emergency), you must make an exception to rules like "don't talk to strangers." I don't know is the riders were park rangers or other uniformed authorities or civilians, but clearly the risk of the woods is greater than that of people, regardless of whether they're authority figures.
I'm glad he's well, let's learn from his experience.