Will the lights be on on every night at Beijing Bird's nest?

I would like to visit the stadium, and would like to come on an evening. I have 2 queries:

1) Is the last admission at 6pm? Or, do we need to be out of the stadium by 6pm?
2) Will the lights be "on" on every night? I would like to see the birds' nest "illuminated".

Thank you in advance.