Take a look at the app - DSLR Camera Remote by onOne Software - the Pro version is for iPhone ($9.99) and the HD version for iPad ($24.99); both are available through the Apple App Store. My understanding is that if you tether your D700 by a wire to a computer running their server software and that computer is wireless networked then you can connect your iPhone or iPad loaded with their iOS software wirelessly through that network and use live view, focus the camera, shoot images and more, all from the iPad. If I understand correctly then aperture, shutter speed and white balance can all be controlled from the iPad. Not the direct camera to iPad control as you (and I) may have wished but if you have for example a laptop that can stay close to the camera and allow the iPad to connect then you have a likely solution.
I haven't used this system but I've looked at the Tech Specs and the D700 is listed as compatible for a number of the features, including Live View. I'm very tempted to give it a go - I just need to persuade one of my kids to lend me their Macbook for a while. They're home for Christmas so I might just get to do this soon.