FePhoenix,
For inspection work at distance I would seriously consider using an assistant with a pair of binoculars. If you want to obtain the best photos there's only two ways to do it, get real close or use a lens that provides greater magnification. There's only so much the gimbal on the H is designed to do and capable of doing and remain effective. It's very much weight limited where the vibration dampeners are concerned, meaning you can't go off the deep end with lenses that are significantly larger in size and weight that what the CGO-3 comes with. The assistant would be quite helpful in guiding the operator to the closest safe distance possible and be a real big help in avoiding guy wires. Those often invisible buggers get in front of you real fast and will bring the aircraft down the first time you hit one.
As for the GPS battery, I'm not certain but i believe the H-480 GPS module already contains a small back up battery.
Something to consider; your FPV camera idea is a good one but to incorporate one introduces some new issues. We should understand the H-480 is designed as a system, where each part of the system impacts other parts of the system. The electrical system is designed to output "X" amount of power, with that amount of power determined by the aircraft's weight. The battery is a substantial portion of the aircraft's total weight, so the size of the battery was selected based upon maximizing the potential flight time but not add so much weight it would impact power performance. On that basis, the addition of an FPV system would create two negatives. One is additional weight, where additional weight places a greater load on the designed power system. The other is the power drain that would be incurred by the FPV electronics. If the FPV drew power from the flight battery the usable flight time would decrease. A small secondary battery could be applied to power the FPV system but that adds even more weight, further impacting flight time and the power system. Multirotors are all about "balance", where that balance references the compatibility of all the associated components. Add too large a battery and the additional weight of the larger battery can actually decrease flight time because more power is demanded of the system just to lift and carry it.
A lot of effort goes into designing a balanced system. Most of them usually have a little room to carry some additional weight, but the additional weight carried always comes at the expense of available flight time, and when too much impacts aircraft stability. Same applies to any accessory added that draws power from the flight battery.
Forgetting to stop the video is something we have all done. The requirement to stop the video has been present with pretty much all of Yuneec's multirotors. They even make mention of it in the 920 manual, something they should have done in all the other manuals but didn't. OTOH, over time each of us becomes more knowledgeable of the systems we fly and small things like stopping the video become less and less of a problem because we learned it's something we need to remember and do. Shoot, there's been more than a few flights I've forgotten to start the video.