Teachers really do not need much training or preparation before they implement digital storytelling into their classrooms. I would say that a teacher should make his/her own digital storytelling project as an example for students but also as a way to learn methods for putting one together. Teachers should plan for time in computer labs and a learning curve as many students will never have done a project like this. I do not think it is ridiculous for teachers to assume the "learn as you teach" method a little bit; this project could certainly be used to promote problem-solving, so teachers do not need to spoon-feed the solutions to students. Allowing students freedom to explore different ways is good. Teachers should have a basic knowledge in order to help students with questions, but the purpose of digital storytelling is not so much about the technology as about what is being produced by the technology.
Digital storytelling definitely holds much potential benefit for shy, quiet students who do not like public presentations. This is a way to share with a class in a creative way without having to stand in front of a group of peers, which is typically very uncomfortable for many people. In the case study, Glenna (the shy, quiet girl) was very comfortable with posting her digital storytelling project to YouTube where her class could view and comment on it. It is a "safe" way to open up among peers.
Outgoing students would not necessarily be harmed by a digital storytelling project. It probably would not have the same impact for them, as it would for a shy student, but is a new way to present ideas and learning, which can benefit all students. Outgoing students would potentially enjoy the opportunity to express themselves in a new way and however they want. Teachers could have an in-class discussion about the projects as a way to allow outgoing students the opportunity to share their thoughts in a comfortable way for them as well.