The Story behind the Original iPhone

So I've read several article within the past year about Verizon passing on the opportunity to be the exclusive carrier of the iPhone. Why did they past on the opportunity, and why did Apple pick AT&T? What's the story behind the original iPhone, and what does the future look like for the iPhone on Verizon? I heard that some international carrier's are considering to terminate their contract to sell the iPhone; do you think Verizon will renew their contract? Also, do you think Apple has a biased preference for AT&T because they were willing to agree to their terms for the original iPhone?

I'm looking into purchasing the iPhone, but I'm uncertain on which carrier to choose. I know Verizon has great coverage, but I don't want to pick a carrier that could drop the iPhone in the future, and AT&T looks like they will always have the iPhone.