Some of the items are already implemented and some are planned.
Let me address each one here:
How do I see all Projects that don’t have a Next Action assigned?
That is not yet implemented.
How do I label something as “Waiting For”?
Not implemented. For now can be defined with tags.
How do I give something various tags/labels (other than the red/orange/yellow priority tags)?
You can add a tag by typing #tagname inside the node’s text. You can then search tagged items in the search-box. This functionality will be extended. We are also planning to add labels or similar functionality.
How do I define Next Actions at various sub-levels and sub-sub-levels of the hierarchy?
The first incomplete child of a Project is a Next Action. You can turn an action into a Project, then it becomes a sub-project. I will create a more detailed description in the Help soon.
How do I designate something as an Action?
Direct children of a node of type Project are Actions. Children of Action node are of type Node (not Action as it was in GTDNext).
How do I see a list of all Projects?
Not implemented yet
Really looking forward to this one as it is important for doing GTD reviews, and I’m also really looking forward to being able to see a list of all projects and a list of all actions!