yes, you can use the spawnpoint command or if in a plugin do this https://github.com/pmmp/PocketMine-...ne/command/defaults/SpawnpointCommand.php#L74
NO. Read. The spawnpoint command sets it for 1 player only. https://github.com/pmmp/PocketMine-...ne/command/defaults/SpawnpointCommand.php#L74 <-READ!