How does Z-Wave work?

Z-Wave is a wireless technology that fits inside normal household items such as light switches, wall plugs, door locks and thermostats that allows you to communicate with them. You can also use controlling hubs to make these devices "Smart" by having these devices react to things like energy consumption, dynamic sunrise/sunset times, when you arrive or leave for work and so much more. Z-Wave doesn't just give your home the "COOL" factor but also helps you to minimize your carbon footprint.  

How do I get started with Z-Wave?
Is Z-Wave easy to install?
What is the Range of a Z-Wave?
How many Z-Wave devices can I have?