Re: seats reclined for take off?
(subject to airline) With most airlines, seats must remain upright or at the angle they would cope best with structural stress in an emergency.
Seat backs when fully upright, protect the backs of heads from flying debris and allow clear evacuation from a set row if need be.
Even back rows in front of bulkheads, occupied or not should be raised.
If an over head locker collapsed on emergency landing, and one or two seats were out of alignment, the locker could veer off to an angle and cause far mor injury, or block an ailse, etc. Also parts of the aircraft are designed to move in impact to protect the structure so seatbacks in the wrong position could contort the shift motion and momentum and cause problems.
If a seat will not stay upright with someone seated in it, the seat should be vacated, and not used, and any passengers in the row behind should be moved if it may impede their exit.
Sleeper seats have a 'safe' setting also, and this depends on what the stress engineers have deemed as safest for these seats during the design process.