This quest where you have to sneak around behind Loredo's place, the guard standing by the back door (taking a wiz) always turns around and see's me before i can reach that ledge. Is there a specific way to do this without getting noticed because he doesnt seem to move unless i do ?

Go straight at him and stun him

I got caught the first time and thought that was it then continued on until I couldn't make the harpy trap (didn't jump the wall to get it) I read about that then reloaded a prior save and had no problem going around the "ledge"(rock) to the right of the guard and then was able to stun the gueards!! search all the area if you make it that far.....you don't really need the trap I learned just watch the Harpy battle youtube video!!

If you press Z right past the first guy, you will see an obstacle around the corner between you and that whizzing guard. go around the obstacle and you should have no problem. When you are in the backyard, there are a few more obstacles to watch for there too. Sorry, I cannot remember if there are three or four guards back in there to coax to sleep on duty.

Yeah. You are knocking over a bucket. It took me forever to figure out why I couldn't get to that one guy.

Experimentation suggests to me that you have to run straight at him; if you pause at all, he'll turn around. Even if you run straight at him, there might be some random chance that he'll turn around. If you go towards the ledge you need to climb to, he'll also turn around.

Probably because you knocked down a bucket, like two have mentioned. If you avoid it (i.e. don't walk close to the edge of building) he will take over to whiz

No. Tried that. He'll also continuously urinate for minutes on end if you don't approach at all. There's probably a trigger line roughly parallel with the ledge on the right; once you cross it, you need to keep going.

I had some trouble in this one as well. The answer was simple - just hug the right wall - not the left. From your hiding spot at the corner, walk across towards the far wall, before walking towards the peeing guard. Then you can stun him without notice.