How to teach your kids what you believe, when you're not sure

So I have a rather difficult situation developing.  I have a 4 year old son asking increasingly complex and probing questions about everything.  This spans many things I'm comfortable with, such as why does the rocket shoot so high in the air when I stomp on the balloon looking thing, or what does CSS mean?  (He only knows because he asks everyday what I'm going to work on, and I tell him the same thing I tell my team during stand-up, slightly shortened.)

He then asks things I have a harder time with, such as why did God make it so we can get sick?  Why did God make bugs that bite us?  I have complicated ways of explaining these things to myself.  I'm comfortable, mostly, with my understanding of these things.  That means I can give him increasingly larger portions of my understanding as I feel he's ready.

But then he asks things like, what do Tyrannosaurus' do to people?  Simple question right?  I could just queue up Jurassic Park and answer that question for good.  But the truth is, I'm still not at perfect peace about what I believe.  I was raised literal 6 day Creationist.  I have severe difficulties reconciling what I now know, and what I once thought.  I want to believe in a simple interpretation of Genesis, because most of the time, I like simple, and I like to think I can understand the basics of a thing, especially one so important as the origins of life.

But I don't want to cling to an interpretation of the Bible that I'm not confident it instructs us to hold.  I have enough faith to believe what the Bible says, because it describes reality as I understand it.  I have wrestled, and still do, with how we could have a sense of humor, a sense of the infinite, a desire for eternity beyond progeny, a physical body that couldn't survive a cage match with any number of supposedly near or distant animal relatives, for the trade-off of a brain that only in the past couple thousand years has given us the tools to really tip that balance.

So when the shows he so desperately wants to watch tell him Tyrannosaurs died out millions of years ago, I confirm it.  I tell him dinosaurs lived a long time ago.  He's 4, so 2 years ago was a long time ago, and he tells me as much all the time.  Dada was a little boy a REALLY long time ago, so I'm sure to his understanding, I won't be wrong, regardless of what he ends up believing, for at least another year or two.

 I still feel like there's a lot we don't understand, but I hate to see that as the only justification for saying that we'll one day reconcile physical evidence with a 6,000 year old universe and 6 x 24 hour day Creation.  Is it possible for me to hold on to that possibility while believing it's probably not so?  Is my belief in God's gift of eternal life dependent on my understanding of the speed of light, when it comes to understanding what we see coming from billions of light years away?  I don't think so, but it doesn't make it easy to know what to say to Jacob.