Everything you need is included and in good working condition. I just changed out the original derailleur pulleys for alum ones, they have maybe 20 miles on them.
It charges thru the junction box and you do not need to remove the seatpost. I will have 11-28 dura ace cassettes available soon too. The item "Shimano dura ace di2 7970 Shifting Group" is in sale since Saturday, November 10, 2018. This item is in the category "Sporting Goods\Cycling\Bicycle Components & Parts\Build Kits & Gruppos".
The seller is "tdr2758" and is located in Norman, Oklahoma. This item can be shipped to United States, Canada, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Australia, Greece, Portugal, Cyprus, Slovenia, Japan, China, Sweden, South Korea, Indonesia, Taiwan, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Mexico, New Zealand, Singapore, Switzerland, Norway, Saudi arabia, United arab emirates, Qatar, Kuwait, Croatia.