1. Ours are in the back galley and thus there is no switch in the flight deck. It will turn itself on with a large enough G Force or by coming into contact with water, or it can be manually turned on by the Cabin Crew.
2. You're not going to find this information as it will not be published anywhere and will be known only internally at Boeing.
3. You want the Centre of lift to move forward upon stalling and not aft, to make the aircraft naturally pitch down to aid exiting the stall.