Have you checked with the Zenmuse Assistant software that you have actually got the HDMI turned on? You might have to adjust the TX end point until the red bar appears.
From what I understand DJI have approximately 300 employees, about 80-90 of which are in R&D. This is just for Multi-rotor and Helicopter. With this kind of resource the future should look interesting!! HobbyKing is "no" comparison.
I think the Bluetooth module will link to their existing datalink, so 2-3km with 2.4ghz or 6-10km with 900mhz (900mhz not allowed in Europe). So, iPad Bluetooth to BT module, BT module connects to Datalink, Datalink 2.4ghz on multirotor about 2km.
I'm sure DJI are doing this through the App Store, and if I was them I would also charge for it. To get some of the development costs back.
it normally takes a week or two for the product to actually appear after DJI release it. So let's see.
Contact Martin here:
http://www.buildyourowndrone.co.uk/aboutus.asp
I think he's your closest "DJI Authorised" dealer. Explain your situation, he will probably try to help and he's a really nice guy.