Is it possible to deactivate rigidbody without deactivating the entire gameobject?
obj.rigidbody.active = false; seems to deactivate the entire object… o.O
Setting a component's .active is actually setting the active state of the game object it is attached to (exactly what you are experiencing). using .enabled will do so for a specific component (what you want to do). However rigidbodies don't have an enabled property.
Setting the isKinematic bool to true will stop the object from doing normal rigidbody stuff (gravity, movement, bouncing off things etc). It is basically specifying that you have an object that you want to move around in code.
As far as I know, having an object with a collider but no rigidbody means that the object is treated as static collision geometry and it optimized as such. Moving such an object around means that the optimizations need to be performed again (which is far more inefficient than treating the object as movable and not doing the optimizations).,