RE: Good cam for Zagi? (any of these?)
ham license is strictly a tx power thing, as reception distance is controlled by rx antenna. There's a test from a set of questions. Do a google search, there's plenty of info.
I suspect that the 500mw 2.4ghx tx set is lighter than the 100mw 900mw tx set or at worst about the same, because you only need a two cell battery, rather than a three cell battery.
Any plane you fly with a camera should be powered with lipoly cells to off set the extra weight and give decent flight times. Also look at a brushless power setup, as it will help too. A speed 400 power zagi should fly fine with a 3 cell 2ah pack.
Lipolys take at least one hour to fully charge, any faster and you will hurt them, you need a special charger, there are a lot out there now.
If you are worried about cost, get the kx 131, it's a great camera.