This is unlocked with natural progression. It will come after completing the 30th level.

This is the hardest achievement of the game. Remember to dodge, dip, duck, and dive. You'll learn by trial and error what works. Remember that you have rockets and to use them - especially when you have the Choppers with 20 or 40.

For the most part, the game isn't too hard to get five stars on. Especially since you can use a better chopper for the earlier levels once you unlock it. Learn which ones to use the small, fast helicopters and which to use the big slow ones. Levels with the injured people for the most part can be done with both types.

If you're willing to buy DLC, the Albatross and Night Avenger are very helpful for this achievement.

For further assistance, refer to this thread.

Escape missions are where you start with people to pick up and have to get to a hanger, bunker, or aircraft carrier. Basically, you can't shoot, smash, or blow up anything or anybody. So use something with good speed and armor. The only level that is difficult is the last escape mission.

If you're willing to pay for DLC, the Night Avenger is great for this.

I got this on the level after the first zombie one. You can get it there while still completing the level in the required time. If the timer runs out, it doesn't end the level. Zombies, Chickens, and Goats do NOT count. Infantry Soldiers and RPG Soldiers do. The achievement will pop as soon as you kill the last person.

This is easiest to get on the first level. You save Scoop and his camera man. Just land your helicopter on one or both. If you are having trouble smashing them you can get them to board your helicopter then crash into the ground. Hard. The achievement will unlock upon level completion.

This is fairly self explanatory. If you die or restart the level it counts towards your progress.  If you are going for five stars on all levels then this should come easily.

This achievement is somewhat difficult. The hardest part is getting the injured man. You'll basically need to just practice and try over and over again. You'll get better at the controls and sooner or later you will get it. The rest of the people are super easy to pick up.

If you're willing to buy DLC, the Albatross chopper is great for this achievement.

He's very easy to find. If you see a billboard or his news van you know your close. Sometimes the pilots will say some remark about him (which means you've found him).

On some of the levels you only have three spots. So you may need to try to land so only scoop gets on, kill the cameraman, or come back later on with the four-man chopper.

If you die or restart the level it counts towards your progress. My stats only show about five thousand including zombies. If you are going for five stars on all levels then this should come easily.

There are chickens throughout the game on various levels and you'll probably kill about 400-600 by the time you complete the game. The first level of the second section has a spot right next to the gas station (left) where 15 chickens spawn. Kill them, get the area off the screen, then go back and they'll have respawned.

If you really want to, you could get this in the first zombie level. If you do the level naturally, whether you five star it or not you can get 400+. You have to complete the level for the kill counter to count. If you kill 900 but you restart the level, it will not count.

This one was quite tricky. You have to make them faint and then kill them. In order for the progress to count you have to either die or complete the level. On the first level of the second section there are 15 at the start. Using this location, you'll only have to kill yourself or do the level 7 times.