Basically every MFI gamepad with extended layout (2 additional analog sticks) should work. Development was done with the Moga Ace Power and the Stratus Steel.
You will be in good hands in the english board for Parrot drones like the AR.Drone: www.drone-forum.com/forum/
No - Apple doesn't offer that, but there is a free lite version with basic functionality available:
Download the lite version of the App from the App Store.
Watch the video demonstration of the app. You will see the key features of AR.Drone Sim Pro.
Scan this QR code
to download the app
Download for iOS
Download for Android