1)Optional Pipe bracket makes adding and removing cup from pipe easy.
2)It is not required but will save you time and make things a lot easier for you. If you mount directly to pipe, you ruin your system if you ever remove the cup. The brackets lends a lot more flexability with your system.
3)The best way to water your adult chickens.
Chickens drink from the cup, which allows the right amount of water to come into the cup.