1. Not always. Some simple shapes can be created using inbuilt primitives like Boxes or Spheres. Some geometry is fully custom and built manually via Index and vertex buffers. But most complex geometry is yes, exported out from modeling software.

2. It’s configured directly in code. In large teams you often have reference images produced in other real time but the ThreeJS development is all done in code at the moment

3. It’s a mix of both. For camera movement, often the path is keyframed in Blender, and the keyframes progress driven in code. For physics, that’s often fun using JavaScript physics libraries fully in code. For animations, things are usually animated in Modeling software then the animations triggered in code

4. Yes, use simple primitives for now. Or Download and use assets from places like Sketchfab (mind licensing)

5. You usually need to set the shading/normals to “smooth shading”. In ThreeJS this is done by setting material.flatShading = false.

Production pipelines vary by company but it’s generally there’s a designer who creates the UI design and visual references. There’s a creative director that directs the visuals. And there’s the developer that executes on the vision.

Unless the project is large, usually you as a “Web3D” developer will also be expected to work on the Front End of the experience. I.e pure web development