The pictures were definitely from Aaron's backpack. There was a picture of Rick and Carl (I assume there are other pictures with more people in them, but the camera only showed the one with Rick) which was new. Aaron probably took photos of people after Michonne's comment about the lack of people in the photos. He mentioned he develops them himself.
I don't think the Wolves were even aware of the Alexandria Safe Zone until they saw those photos. Remember, Aaron said they were 50 miles away from home, so it's not like the Wolves would stumble upon it immediately. But now that they have photos of the place, they're sure to be on the lookout of the walls, setting up a conflict to be resolved in Season 6.
I agree the wolves were not aware of ASZ or else they would have already caused those people lots of problems even before the arrival of Rick and Co. The wolves just haven't reached ASZ yet and it seems pretty clear to me that the wolves and ricks group have been heading the same direction on a similar path. I'm thinking the wolves have seen our group but they didn't attack them yet because maybe there were only a couple of wolves spying on them at the rime and they saw how strong our group is .
When they see the photo of Rick, they recognize him and now they know where to go to find him. Or at least they will know where he is when they start to see things recognizable in the photos. Also, it's possible some wolves have known Rick before....maybe from terminus or even Woodbury (?). Thre had to be survivors from both of those camps despite the destruction. Really, I think it might be more interesting if we see a somewhat familiar face from Woodbury. It would go a long way to show us how lasting consequences in the ZA would be.