re: Purpose of Projects List
As David Allen points out, the purpose of the projects list is two-fold:
(1) It is the one place you put a stake in the ground that shows your commitment to some multi-step outcome. This is the list that governs most of what you do every day. It is the list of things you are working toward by completing your actions.
(2) It serves as an "index" for your next actions. As you capture tasks under each of your projects, the next, kick-start action serves as a "bookmark" for where you are in completing that project. Of course, you need not only have one action from each of your projects on your action lists, but you should have *at least* one.
Hope that helps.