removing breast before roasting rest of duck?
I would actually recommend you remove the breasts, regardless of when you will be cooking them.  It is very difficult to get the duck breasts to a perfect 125–130°F, the legs to ~15° hotter, and to simultaneously render excess fat and crisp the skin when roasting the bird whole.  Cooking the individual muscles separately greatly simplifies this.  Also, with duck, there is (in my opinion) relatively little advantage gained from roasting the individual parts on the carcass, other than tableside presentation.