@tgauchat has given you excellent resources already. 
Reading those should answer most of your questions.
The one thing I would add as someone who worked as a network engineer is that all the official technical documents (from the zigbee alliance for zigbee and the Z wave alliance for Z wave, which are the certifying bodies for both) say that different devices will take different roles in the network. For example, battery-operated Devices don’t usually act as repeaters because it would use up too much battery life.
And smoke detectors, even if mains-powered, typically do not act as repeaters because they are considered priority devices: you don’t want one to delay announcing that smoke was detected because it’s busy passing on a message for a light switch somewhere.
In addition, individual manufacturers are given some flexibility under the protocol specification as to whether or not they will implement repeating. But it should say in the product specifications for each individual model whether it does or not. For example, the makers of the Sengled zigbee smart bulbs are unusual in that they have chosen not to have their lightbulbs repeat, even for each other. Their devices are still fully certified zigbee lightbulbs, but they do not act as repeaters.
So it’s just something you have to check for each model you buy. But most mains-powered devices will act as repeaters for the network they are part of.
Which brings us to Hue. The Hue bridge forms its own mini network–bulbs attached to the same Hue bridge repeat for each other, but not for your other zigbee devices. Again, details are covered in the links that @tgauchat already gave you.
Protocol Specification Resources
BTW, in network engineering, the “rules” you mentioned would be called the “network protocol specification,” and that is the term used by all three certifying bodies who define and maintain the ones that typically come up in a SmartThings context: the Zwave Alliance, the Zigbee Alliance, and the WiFi Alliance.
Within each specification there may be multiple “standards” which in turn identify different “profiles.” Zwave only has a single standard. Zigbee has many. SmartThings uses the “Zigbee Home Automation 1.2” profile.
Official Zwave Specification:
http://zwavepublic.com/specifications
Official Zigbee Specification:
http://www.zigbee.org/zigbee-for-developers/applicationstandards/zigbeehomeautomation/