I would however recommend that you double stud the side of the door and at least double up (up on edge) 2-2' x 4's above the door way for a header. It will help to stiffen the doorway so your door should operate better year-round, if not it could flex on you and be hard to open at times.
Thanks for the suggestions, although I have no idea about any of it myself, I know hubby is a perfectionist, so I have no doubt he has thought of that with the door. We will also be well insulated for the very cold winters here. There is still lots to do to get it finished, but I have faith in him...