His Q still resets his auto attack.
W grants vision.
You can cast W inside a wall and it will not have a visual warning
E will cause Mist Walkers to jump on enemies in fog or who are invisible.
Can use E to stop Walker or Maiden from auto pushing
Maiden will not push into towers without minions
Can cast maiden on walls similar to flash to extend the range
Turret aggro priority Canon>Walker>Maiden>Minion
Edit: Walker takes aggro before Maiden