A piston can be broken using any tool with equal efficiency, and will always drop itself.
Pistons are always placed facing towards the player. When powered, the piston's wood surface extends outward by one meter for 0.15 seconds, which can be heard within a 31 x 31 x 31 meter cube centered on the activating piston, the piston can shove up to 12 objects in a line with it. Any entities in the path of the extending face will be shoved with the objects. If there is no place for the entities to go, the object will shove through the creature, suffocating it if the object is not transparent.
When a piston loses power, it will retract by simply pulling its face back instantly, unless it is a sticky piston, in which case it will also pull the object in front of the face.
Sticky pistons only stick to an object when retracting, so an object next to the piston face can be shoved aside by another piston and sticky pistons cannot hold falling objects horizontally against gravity. They also do not pull objects 0.1 seconds later after shoving them. This can be done by using a 1-tick on pulse.