Introductions, Startup, Budget

Hello. I am new to SketchUp and I need your help in getting started. I need SketchUp to create models to be analyzed by EnergyPlus and OpenStudio for Building Energy Modeling, particularly passive solar residential and small commercial applications. Along with SketchUp Pro, what other extensions do I need and how much should I budget for software purchases? I need to go back and forth between 2D and 3D; model walls, floors, windows, doors, roofs; different HVAC types and configurations; lighting ; have clients view and markup the 3D models; and optimize the designs.

Any input would be appreciated

Hey Henry (and to any others looking at this forum post and wondering about the same info), a detailed reply can be found in this other post: Natural Solar Heating Cooling & Lighting