:: As for flying and skydiving, my instinct is that as long as you have a good view past the fuselage and are up sufficiently high that your photo rate won't need to be firing all that quickly if you're just after the ground below you.
Your field of view is going to be wide open, so assuming that you're shooting with a lens that takes advantage of that, as long as you keep pointing in the same direction during freefall, things ought to link just fine, I'd think.
The nearer you are to a subject, the more often you need to fire, meaning fewer photos at higher altitudes.
The same would apply to shooting a wall synth moving down a street and slowing to get good overlap on trees or signs which you want to be reconstructed.
If you're shooting aimed at the horizon, though, while moving forward, rather than down (and especially at lower altitudes), then yes you'll need to fire quite rapidly to get adequate overlap.
You might want to keep an eye on UAV and KAP synths.