Only just seen this thread.
I love the idea of an integrated iPad mini, however it would have to be removable and not look stuck on. Getting the music to the HU won't be an issue as you'll need an aftermarket HU (unless you want to do the Bose hack) and they pretty much all have BT anyway.
Power would be a great bonus, but not necessary as the battery in these things last longer than you'd be driving for anyway, unless it's a 3G version and you're using a navigation app.
I really like the clip in magnet thing in a previous post. Easy to remove, sit nice and flush and minimal fabrication work. Don't need to worry about security because you can lift it out really easy
However, I'm not sure why people are worried about the security of it in a fixed setup. You won't be able to see the home button and it'll just look like a standard OEM sat nab to the untrained eye and I highly doubt these creeps who go about breaking into cars know which cars have which sat nab systems.