When is appropriate to use the workflow process?
The workflow process is appropriate to use in a number of situations. For example, when work is delegated, then workflow can be used to organize the delegation. It should also be used when there is a need to audit and approve content before publishing.

Is the number of nodes in the workflow limited in any way?
By default, the workflow consists of two steps: editor(create)--> moderator(approve)--> publish. However, any number of nodes can be added to the workflow as appropriate.