No. You can only do it on offense.
No you can't.
Yes, the assistant can call a timeout, players on the court can also call timeouts.
they will give you a penalty
The coach can call a timeout
No, the only times where one can call a timeout is when their team has possession of the ball or when there is a dead ball, which means the clock is stopped (out of bounds, foul called, etc.).
yes. but only on a dead ball. You can't call a defensive time out when the ball is in play.
Anytime the team possesing the ball wants to as long as they have time outs left.
a team can call 20 second timeouts or 1 minute timeouts (full)