Autodesk Revit MEP

[#1]

How do I create a viewport from a floor plan

[#2]

Are you wanting to get the FloorPlan view onto a Sheet?  If so, open the Sheet view, then in the Project Browser, pick and hold on the FloorPlan view name, drag and drop on the Sheet view.  If that isn't what you are after, then please give a bit more detail.

[#3]

The "viewport" boundaries are controlled by the Crop Region. Under the View's properties, you can turn it on and adjust it as necessary.