2 QUESTIONS: ZigBee3 and/or Z-Wave & ST or HUE? Help (dec2018)

You might also find the following thread of interest. It discusses the kind of features that different device classes might have, and why a person might want a particular feature. So it can be helpful before you plunge into reading about light switches or motion sensors or contact sensors, because you will have a better idea about why a manufacturer is showcasing a particular feature.