I'm afraid that my attendance will probably be irregular.
I'm not planning to attend Koichi's birthday party.
Could you put me on another flight? I really have to attend the annual G8 leaders summit.
The people who exit their seats at the end of the show are the number of people who showed up, not counting empty seats. This is the true attendance.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Just note the しゅつ gets changed to しゅっ, as many つs do in this situation.