Resolved Image Marker Events?

Using Image Markers, I'd like to call some functions when they are recognized and when they are lost. I haven't located documentation on how you can tap into these events, other than being triggered based on the marker's children becoming enabled and disabled. Is this the intended approach or is there a better way?

Is there a deeper dive tutorial on Image Marker use?

Is there API documentation for all these new MARS objects?

Thanks.