ADS - I may have missed a post, but I always remember ADS stood for Aerial Delivery System and if I remember correctly, the arms were fitted with micro-switches that inhibited the ramp switch.
Snatch - This was little more than a rope (abseiling rope I think) fitted with a grapple hook that trailed behind the aircraft. Height and speed and steady flying were the secret otherwise the hook would flail and strike the ground resulting in the hook breaking free and the rope recoiling and striking the aircraft. The hook used to trail abut 35ft below the a/c. The rope was then wound in by the AD troops and jammed in a series of cleats until another could be secured and finally winch in the rope attached to the package, all while the aircraft was kept fairly steady and slow.
My first ever drop on STS was a jungle line and it snapped resulting in a MALDROP report being raised.