Null Engine collision detection

For the null engine, do I need to run scene.render()? I am only going to be using it for collision checking and never for any form of animation.

Yup you need to call into it as this will trigger all our internal process making collision detection and such.

Perhaps you can call it automatically as well - I meant manually

So do I need to call it whenever a meshes position is changed, or only when the scene is initially created?

whenever something changes is probably fine