Can 2D architectural Plan be converted to 3D using 2D as base?

Yes. Use AutoCAD's "Extrude" and "Revolve" commands to turn2-D designs into3-D models.

Yes, It is possible that a2D architectural Plan be converted to3D using2D as base

Yes. Actually the proper way to accurately model an architectural assignment is to develop it from the2D plan. All modelling softwares can import2d dwg (Autocad file).

yes u can also import to3ds max for better rendering