You are now where many of us are or have been. Congratulations on making it this far. Honestly, I don't think many who allow themselves to question their JW beliefs to this extent (to actually, <gasp>, do independent research!) last much longer in the bOrganization.
There have been extensive discussions on all of your concerns here and on other web sites over the years. One site that has helped many come to terms with these nagging doubts is freeminds.org. Give it a look-see.
I'd like to just offer a few rebuttals to some of your points. You can look up the information for more detailed explanations
But on the other hand I can't ignore things like the fact the organization is growing while other religions are on the decline
Growth is no indication of God's approval. In the US, Mormons are growing faster than JWs (JW growth rate is actually decreasing) and worldwide Islam is growing a gazillion times faster than JWs.
JW's have learned many things about the bible that other religions don't know
That's debateable. I used to think the same thing, until I started really looking into it. You mentioned 1914 for example. Do you realize how many JW teachings stem from or depend on this one? You've already mentioned that there's no historical evidence that Jerusalem was destroyed in 607. If 1914 is wrong, then not only does it show they don't have God's approval (this is no minor issue to be wrong about) but their whole doctrinal house of cards tumbles.
Also their seems to be a certain unity and cohesiveness within the organization
This is a point that I used to believe wholeheartedly, and nobody could tell me differently. But is it unity if you're afraid to voice an opinion that's even slightly different from the GBs? Is it unity when you're made to feel disloyal for even THINKING they might be wrong about the tiniest issue? People have to put on a smiling face at the meetings because if they don't, they'll be labelled as spiritually weak. Also, ask the thousands who are disfellowshipped every year for making human mistakes how cohesive and loving the organization is.
The preaching work is done all over the world by witnesses.
It they're not preaching the truth, it really means little. Besides, the world is a mighty big place, and there are HUGE chunks of it that've never heard of Witnesses. It's not nearly as extensive as they'd have us believe. (Almost 1/3 of the world's population lives in China and India, where there is virtually no preaching being done by Witnesses)
Keep up the search, Leander. I have little doubt that before long you'll be on this side of the fence, wondering how you ever bought into all that stuff.