That is a creative idea. I'm not sure I believe how easy it will be to air-drop chickens and have them land without broken legs / general death, cuz the plane would have to get REAL close to the ground.
Solving world hunger seems like one of the more doable "big dreams" of philanthropy, since the money is already available - it's a distribution problem. IDK if live chicken airdrops are the answer... but hey, maybe!
I actually wouldn't want it as a standard charity model, as it would put local farmers out of business, I'm more thinking of dire emergencies.
As to the height and speed, chickens have a lot of drag. I imagine they'd slow down quickly and get safely to the ground by flapping; just not sure how exhausted they'd be.
Might make them easier to catch.