wasa

1. no
2. no idea. i usually see it work after 3 or 4 hits generally but bad rng can make it take ~10 hits too.
3. you melee attack it. there's a special static "tuning" sound you get on every attempt. if you don't hear this sound then you are attacking something that can't be hacked (no hacked sawblade locusts). you can also melee attack dead locusts which will revive at full health on successful hacking.
4. forever until their death from my experience, they essentially become pets that follow you around and even teleport to you if they get too far from you.