It is interesting to think about the various fictional vampires and hunters mixing things up. Gary Oldman still freaks me out as Dracula. Talk about creeptacular.
In regards to Aro & Alice, I wonder if it is more that her human life doesn't interest him - he is so obsessed with her immortal talent; he can't be distracted by something as trivial as human memories.
However, if Aro had seen something from her human past and it was terrible, I think that Edward, having seen it pass through his thoughts, would have been too gentlemanly to tell Alice about it.