I have done several reading in NY and like Matthew said expectations vary.
Some of the readings involved light and sound cues, rearranging the chairs and music stands at intermission and sometimes reading the stage directions.
Regardless I usually still give calls starting at half hour. Usually there is no AEA meeting involved but there is a form that everyone will need to write their name and AEA ID number on.
Hope this helps!
What, where and when is your reading?