Can a user assigned to a Workflow License fill out and store a Form that then triggers a workflow?
The user which has a Workflow user license assigned can fill out a form and submit it. The Workflow process is a separated process so yes, this will work.
Which of the Desktop Apps function and to what degree under the Workflow License?
As a user assigned to a workflow license no functionality works, that will store or edit a document in DocuWare, only searching is available. Do you have any specific functionality you would like to use?