Major spoilers ahead

After completing the Thieves Guild quest line you're told that the female nightingale (I've forgotten her name) will return to Nightingale Hall to live there. She earlier mentioned that the parts you see are but a glimpse of the Hall's secrets. Upon returning there I've found the hall to be cleared of rubble and a number of beds, bookcases ect installed. However the female Nightingale isn't there and I've waited for some time. Secondly, and more interestingly, there is a chain hanging from the entrance to the altar area which, when activated, states 'You can not use this at this time'.

So this raises the following questions:

1. Where does the female nightingale go? Can you run into her in Skyrim? She did say she would leave to do some old fashioned thieving....
2. What does that chain do? Or was it a part of an older quest?