I use my i6 through my E2 and Prime powered using the USB 3 camera connection kit and externally powered via the lightning socket only on the USB3 kit.
For portable use, whilst i have not tried it, cont see why it would not work with an external battery pack - we have a couple of 5000mWh TPlink battery packs which work very well for other uses.
The length of the lightning cable on camera kit is a bit short to prevent a birdsnest of cables, but you can get lightning extension cables that, whilst i have not tried with camera kit, works well with another lightning accessory i have, even when 2m long.
Last edited by Ian; 2017-04-29 11:29. Reason: Clarity it's the USB 3 version of the camera kit