How does DS1's communications system work?

How does the communications system work with so little power?

Satellites like DS1 can communicate over tens of billions of kilometers using only 20 watts of power. Satellites concentrate all available power into a narrow beam. Secondly, satellites carefully direct this narrow beam in one direction, right at a certain receiver on Earth! Also, the antenna that receive the signals are much more sensitive than, say, a car antenna, and have very complex computer programs that separate out the satellite's signal from the noise. The antennae in the Deep Space Network that are receiving the signals are also very large, so they can bounce spread out radio waves into a signal that is readable.

What is the Deep Space Network?
How often does DS1 communicate with a ground station?
How much power is available for the communications system?
How is data put on radio waves?

Why do communications get harder at greater distances?
Why does the data transfer rate have to drop with distance?
What new communications features does DS1 use?
How do the instruments and sensors coordinate sending signals?
What kind of data is DS1 sending back?
How is extra data sent in the radio signal?
How much data will DS1 be able to transfer?
Is there only one stream of information coming from DS1?

How much power does each part of the system use?