Which events are triggered when I draw, for example, a polygon? Like when I define the vertices of the polygon by clicking? And how can I capture these events? Or, better: Is there any documentation in the web that covers these issues?
The events for a vector layer are documented in the docs at http://dev.openlayers.org/docs/files/OpenLayers/Layer/Vector-js.html#OpenLayers.Layer.Vector.events
Maybe the events of the DrawFeature controller will help you too: http://dev.openlayers.org/docs/files/OpenLayers/Control/DrawFeature-js.html#OpenLayers.Control.DrawFeature.events