Re: how we can define registraion and die cut objects to avoid traping
If you have the die objects as a separate ink (you can make an ink called "Die" in the Designer Book), you can set it to be Technical in the Ink menu. Technical inks can be ignored in the trapping.
As for registration, I've asked about having a way to define an object as "registration" so that it dynamically changes if inks are changed, and can have special properites (like getting ignored by the trapper), but have never got a very good answer.