"Why is a team charter important?"
In my opinion, the real value of a team charter is the exercise that you go through to create it. It forces you, as the project manager, and your team to discuss how you're going to work together. It forces you to agree on the project goals and the roles and responsibilities of each of the team members. Unfortunately, if you don't create the team charter, most of the time you also don't go through the thought process to figure out how the team should function.
"Why do I need to have a technical environment plan?"
I think the technical environment plan is critical. We're all communicating and working using technology. Unfortunately, even within IBM, we're using different software programs and tools or we're on different levels of those programs. When we're not on the same levels or using the same programs, we have communication problems. The purpose of writing a technical environment plan is to find those areas where we're not on the same software and fix them before we get to a critical point in the project. This is really just common sense.
The place we really see problems is with our suppliers and customers. Many of them aren't running our standard products, and some of them don't want to be. In those cases, we need to decide early in the project how to best communicate with them.
Let me give you a bit of advice about the Team is High Performing key. When I was managing the integration project for Coppets-Close Hotels in the UK, I learned first hand how powerful it can be to have a truly diverse team: diverse in style, in nationality, in gender, and in life experience. And I also learned how hard it can be to bring such a team together, how easy it is to convince oneself to take shortcuts in these efforts, and how tiresome it can be to continually display the leadership that binds the team together. Do not let these challenges discourage you. Fight for diversity on your teams, and fight for the time and resources you need to build trust and communications in your teams. I guarantee your project's performance will benefit.