You can use Slingbox and "sling" it to your iPad, but that means you need a server that would need to be attached to the FPV receiver. Easiest way is to just switch to a Windows tablet or laptop that can directly attach to the FPV gear.
I'm not that familiar with the Nex5. Does it have a composite video out while recording? If not, you can get an FPV kit that has a tiny camera with it like this one.
I just found this product today. I would like to buy it to try it, but its like $1500 USD.
Sorry for going off topic. But am very curious to see if you did end up finding a way of controlling the camera zoom remotely?