Please, advise how to build room constructor

I’m newbie in three.js, please give some advises or samples… I need to build constructor for glass cubicles. User can add default sections each one to a wall, than append another wall… Here visual:

I have a question:

  1. How to build section? It must be created in blender and must be imported to three.js? In which format? Or I must draw it from code?
  2. I need to add multiple horizontal dividers to section. Can I add them to imported model? Or how to do this?
  3. Can I select section and show menu buttons for section?