how long is a turn? is it after all players have move to be consider 1 turn ? can the 2nd players attack on their 1st turn?

1. A turn is as long as the player wants it to be until they end.
(Draw phase, Standby phase, Main phase 1, Battle phase, Main phase 2, and End phase),
but if they are taking their longer then needed its called stalling

2. No, if the starting player ends their turn the next player's turn is considered turn 2 and so on.

3. Yes the second person to go is allowed to attack on thier first turn.

~ Davis