"unresolved" quests

[Tsuken]

I've already run into two strange things with the quest:
1) Both staff segment A and staff segment B dropped off Tallus Holton. I think he is only supposed to drop 1 segment, right? (source: allakhazam)
2) He also dropped the key: H.K. 401, but the bank assistant in HHK won't take it from me. I think you're supposed to get the 2nd staff segment in return for the key. (source: allakhazam). Maybe she won't accept it because I already have the LORE staff segment which I would have received this way?

On another note, does anyone know how to get to Carson McCabe, he seems to be hidden behind a wall but I can't find the secret entrance [You must be logged in to view images. Log in or Register.]