I don't think you will need luck because you are doing the most important thing - i.e. asking questions. That's always a good place to start. I was a JW and I believed that God created everything, evolution was incorrect, all science is suspect, bad things happen because Satan and sin, etc. When you are inside, all outside information is made suspect and unreliable. It wasn't until many decades later of studying topics and sources outside the WTBTS material that you start to realize that (a) the Society often presents their arguments incorrectly/deceptively then (b) proceeds to answer their own carefully crafted questions to make it fit the answer.
For example, the Society constantly proposes that "if evolution is not true, that proves...God." and will also throw in the Big Bang Theory into the mix at times. This is a logical fallacy and it confuses the topics. For one, evolution (change over time), is a fact. We then have The Theory of Evolution as the current and best scientific explanation of the evidence (e.g. fossils, genetics). The Theory of Evolution does not attempt to explain how life originated. That area of study is abiogenesis. Abiogenesis deals with if/how non-organic material could organize (over time and processes) into to complex organic life. Lots of great experiments in that area show promise. Lastly, we have the Big Bang Theory which is the current and best scientific explanation to how the universe began from a high-density state then expanded. Lots and lots of progress being made to get closer and closer to the first instant of the universe.
The reason for pointing this out is that the WTBTS confuses these (and other) topics to make arguments that fit a solution they want to fit - i.e. God did it. They make a further mistake to imply that disproving any/all of the previous (and other) scientific theories means - "God did it". This is not correct as the premise that "God did it" would require its own body of evidence irrespective of the validity of a particular scientific theory.
One thing I would recommend is do some research on some of the above topics - i.e. The Theory of Evolution, abiogenesis, and The Big Bang Theory using sources outside the WTBTS. Here is a good article on evolution you might enjoy - http://www.scientificamerican.com/article/15-answers-to-creationist/. There is a wealth of information out there that do not include God into the equation so you can learn the topic objectively. And, perhaps, you can invite your son on a learning adventure when you feel ready. Maybe you could couch it as "learning to counter the arguments we get at the door". And, "encouraging him to do his own research", as you stated, is an excellent idea.
As for "why is the world the way it is?", that is an important question. However, as an exercise, you might want to simplify the question by removing a supernatural/force to the equation to start and only add it in when it is necessary. Once you do that a lot of things begin to make sense. And, you may find over time that you don't need to add the supernatural into the equation.
For what is worth, "Good Luck".
