Well one way doors only open in one direction. If one way flag was not ticked, the door would open according to the side of the door the player was on.
So by ticking the one way only flag, it goes by the degree property that you set.
SO if you set it at 90degrees, it will (according to the z-axis view(straight down)) rotate counter-clockwise
And with a -90 degrees rotation it will go clockwise.
And will go that way no matter which side its on.
As for locking the door, you can just use a trigger once on the other side of the door to lock it.