HTC and VZW made an agreement to release the phones. The conditions around the release changed on VZW's end and they had to work out the kinks (pricing, plans, etc) After revisions were made, VZW has to resubmit the changes the HTC for review to make sure they are cool with the changes to the agreement. Then the phone will be released. Think of it as a joint business venture.
I think that is highly speculative. There is no reason to believe that it is not a simple supplier-customer relationship between VZW and HTC. I also almost guarantee HTC has no input whatsoever on plans and pricing. From what I have read (all rumors but it sounds reasonable) the details are long term maintenance (service) contracts and details of those contracts to insure HTC (who can actually do the nitty gritty technical work) offers appropriate fixes and updates to the HTC software (firmware and or OS). Now of course you have HTC acting slightly more like a partner in that they are advertising. That is not that abnormal though as they want to have name and brand recognition. Not just for the TB but across their line and across carriers.
