I'll take the liberty of answering for a largish European carrier:
1. As per Average-Punter's answer.
2. Wherever the passenger wishes.
3. Larger devices such as laptops, DVD players will be stowed but you can use tablets, e-readers, MP3 players, smartphones at all times. All devices should be "airplane mode" throughout except for taxi in.
The important point is that the above are part of the airline's policy, approved by the local regulator and this week's EASA regulations. For what it's worth, I believe the above policies both reasonably liberal and realistic.
PM