Looping? (Still need help)

[SiderealStop]

Okay,

I understand how to get something to follow a path. I understand how to do it rather than just knowing what to copy&paste. But what I don't know how to do is loop it so that when it gets to the last path node, it starts again at the first. It gets a bit more complicated than that though. The room is a big circled hallway which is what I have him patrolling around. The player has to go around to the little dips and rooms and flick switches to start up some machines so that the player can then go and open a door (that is in the same map) to the room with all the machines. Once you flick the last switch and start turning the valve that opens the door, I want the grunt to start going after the player.

There could be walls between the player and the grunt, would that be an issue?

Thanks!