If other activities are going on, expect that party guests may wander off, only to return when a new animal is presented. Safari Guides don't mind as long as you know to expect this. Parents who experience the Safari Guide's visit along with their children, really do enjoy it. This also tends to keep enthusiasm from turning into chaos. For those parents who attend and do not wish to participate, have a designated area away from the entertainment for them to socialize, so as not to disrupt the entertainment.
Gratuity is a personal choice.
It is not expected, but it is appreciated.