Re: Picture ettiquette
Chinese tradition states that black frames should not be used for living people, as black frames are used at funerals, and thus can be seen as a wish for that person to die soon. Black frames are all right to be used for people who have already died. All of the pictures of O-Sensei I've seen in dojos have black frames.
I'm not so sure about placing someone's photo directly on top of another one. Personally, I don't think it looks all that good, visually. You could get a frame large enough to hold both photos, and use another piece of paper or cardboard as a "mat" between them.