1- I figured out how to make choppers spawn decently (Start a mission)
2- None of them were frozen , they still tried to shoot me down , took me 2 tries to get the hang of the flying and gunning
3- I believe it does have to be in 1 flight because I just unlocked it at 32 Choppers killed with choppers
As for my first attempts I ended up being killed in 1 shot because my character would damn near destroy the chopper before I managed to hijack it
Anyway , Whats done is done , Achievement Unlocked 10G >.>
YES - Ranked #25 In the World on True Achievements for Ratio! (Ratio is how much effort your achievements take)
--If a game does not take effort you shouldn't count it as an Achievement Aka - Avatar , Fight Night round 3 , King Kong ETC.
Just because someone does not have a high gamerscore does not mean they aren't a pro.