What do "suit" and "cue" mean?

Question

In the following dialog of the film You've Got Mail, what do "You are nothing but a suit." and "That's my cue." mean?
KATHLEEN:
You with your theme-park, multilevel, homogenize-the-world mochaccinoland. You've deluded yourself into thinking you're some sort of benefactor bringing books to the masses. But no one will ever remember you, Joe Fox. And maybe no one will remember me either, but plenty of people remember my mother. And they think she was fine, and they think her store was something special. You are nothing but a suit.
JOE:
That's my cue. Uh, good night.

Answer 1

Suit- in reference to the people who wear suits for work every day. Most often referring to people in government positions, but also those that work for corporations.

Cue- From theater, when someone received a signal and they would go on or off stage. The signal is called a 'cue'. In this case his signal to leave

Answer 2

I haven't considered it

Answer 3

Haven't thought too much about that