Lol. at all these posts.
There is no way Sasuke would be helping Akatsuki that just doen't make any sense. Naruto is a complete pervert anyone remember when he used to go into the girls bathing rooms claiming that he needed to see what the real things looked like so he could use his sexy jutsu properly.
Yamato building the house was cool the guy likes to travel in style, I don't find him to be creepy but Orochimaru as far as the Narutoverse is concerned is the baddest of all badasses and look at him. Besides they aren't near their mission objective yet, they still have a day or two to get there, I think they are still in the fire country which is home turf so they have no reason to be cautious.
No one knowing about Yamato could simply be due to the fact that he is in the anbu and seems to have been there for a very long time and since who the anbu members are is a secret I don't think anyone would know. Besides people knowing about him is not something you can really go on, if I remember correctly when the Sannin were first introduced nobody in Kakshi's group knew anything about them. Besides from the conversation he had with Kakashi and the others I think that most of the high ranking ninjas in the village know about him.
It is also a pretty safe assumption that he is not related to the first. If he was then that would mean he is related to Tsunade and she doesn't seem to threat him like a relative, secondly all of her relatives are supposed to be dead if I remember correctly. Yamato's age would make him much younger than Tsunade so unless she and Dan had some offspring. Anyway we don't know anything about family histories in Naruto, other than Itachi killed the Uchiha clan.