I went to the Emerald Curtain tour last September. I enjoyed it!! The day starts off: where they have you go to the Wicked museum - which is full of costumes and props. Then after that 2 hosts( on that day our hosts were ensemble members from the show) they gave us a quick overview of building a show from scratch and then putting it on broadway. They discuss costuming , lighting, producing , etc. Then after that we saw a quick video. The day was over and the hosts stayed around for pictures, autographs, and questions.
Overall, you don't have to see Wicked in order to fully understand the Emerald Curtain tour. However, if you have already seen Wicked you will enjoy the tour MUCH better.