Quote - Hmm,
regarding the IDL bounce again. Could it be that a surface that has diffuse value of one (and a light grey color but nothing else, no spec etc) does consume none or only little enery of an IDL light bounce? In that case, I would have to do something with the poser surface. But I don't know what.

Could very well be.
Every thing that you get with and for Poser has a default value of 1 for the diffuse, which is just wrong. A diffuse value of 1 means that no light is being absorbed and all is being reflected. That's why setting the diffuse lower makes it look darker.
Of course, that's all wrong, and a value of around 80% - 85% is generally considered to be more correct for most things. They don't teach that in Poser Merchant 101 though and as a result, almost everything you get will be 100% diffuse. I recently bought a texture pack that had the diffuse cranked up to 2.0, to offset the fact the texture was darker than the seller wanted it to appear....

Also worth mentioning is that your diffuse and your reflection (if any) should add up to about 100%. So if you have a surface that's 50% reflective, you should set your diffuse at 50%, and so on. If you have something like a mirror, which would be 100% reflective, you would set your diffuse down to 0.

Now, that's a general guideline for 3D, and not necessarily Poser.

As for your question how to get Poser stuff into Lightwave, you could get Poser Pro, which has a PZ3 scene hosting plugin, but it isn't worth all the little 1's and 0's that make it up, as you have no control over your figures and have to redo all the materials anyway.
So OBJ import really is your best bet. It's very simple, actually, but it's better to import it all into Modeler rather than Layout, make various fixes there, then save it out and send it to Layout via the Hub, which is a part of LW that works between Modeler and Layout.

If you want to try it out though, for now just export all your Poser stuff in your scene as OBJ either separately or as a whole. After that it gets considerably more complicated and I don't have the time to write up a full explanation at the moment. But whatever book it is you have should explain how to use the surface editor, and the people in the LW forum here know all about it too.