I am a complete newby as well and have not even begun the process to build anything yet. I have been keeping up with the parts and pieces that people have referenced in thier build threads so that I can do one of my own someday.
The part you are reffering to so as to not twist up the wires when spinning the excavator is called a slip ring. Below is a link to an inexpensive one from ebay. You can buy them in differnet sizes and with different numbers of wires as well. Hope this helps and good luck with your build. Keep us all informed of your progress and remeber we all love pics and videos are even better.
http://www.ebay.com/itm/2A-12-Slip-R...61066837430988