We have a need to allow the users to open a document from the web application and enter data from the document to web forms. We don't know the monitor setup for the users (dual vs single / monitor resolution). What are some possible approaches to address this requirement.
Your best bet is to start collecting data. If you can observe actual users, great. If not, simulate this using hallway testing. Go to somebody in your office with a single monitor. See how they perform the task. Now try the same with people with multiple monitor setup. Do you see any difference in their workflow? How different is single vs dual monitors? It's important for people to do this at their own computer. If you're uncomfortable with the setup, you're less incline to adjust things. Which seems like something that's important here.
My gut says you're likely to not see much difference between the two. Simply because most monitors nowadays are widescreens which is much wider than what you need to comfortably read most documents. You can probably put both the document window and your edit form on the same screen without much impact on readability.
Of course nothing beats actual testing.