Nothing is stored on the iPad/iPhone, IMO another oversight by P1 as it would be nice to have a smaller jpg that could be posted online as most cameras allow.
On the iPad, I will often screen print the image if the conditions allow for it, (not often), and then just use that image with some snapseed.
From the iPad, you should be able to fire the camera, use Liveview for preview. There are other features I just never used them.
Once you take the shot, the image should appear on the iPad, (a jpg) that you can attempt to zoom in on. The zoom again will not work up to 100% due to the resolution issues. But you can get a pretty good idea. Once you break the connection the images will no longer be on the iPad unless you screen print them to your photos. Each time you make the connection whatever images are on the camera will attempt to load previews to the iPad. Note, if you have a larger card, this can and will take time and often the process will break down and freeze. So I stayed with 32GB cards when I worked with Capture Pilot.
Battery life will be effected for sure on the back not sure about additional heat build up.
Paul Caldwell