How easy is it to kill a drone?
Answer: A drone is basically a gun turret or rocket launcher that moves as fast as a soldier, but can not hide behind cover.
Do you get a higher diamond reward for defeating a defense with a drone?
Closest answer: The originally stated diamond reward is the amount of diamonds you will receive.
If yes, how many extra diamonds do you get for each type of drone?
Closest answer: Without knowing how many diamonds you would have received without the drone, you can't determine how many extra diamonds you're awarded.
If you defeat a defense with a drone, but do not blow up the drone, do you still get the extra diamond reward?
Answer: Yes, you get the same amount of diamond reward whether you blow up the drone or not.
Does the defensive player get to keep their drone if the attacker does not blow it up, but still defeats the defense?
Answer: To be determined; see questions below.
If you successfully defeat a defense with a drone in it, do you get more drone parts rewarded whether you blow up the drone or not? Do you get more drone parts from defenses that used a drone?
Answer: Not sure, but it doesn't seem to make much of a difference. Maybe it does have to do with the opponents drone parts inventory??
iPhone 4, usually.