I recently had a single daguerreotype hung in a large group photography showing. I presented the dag in a wall mount frame with a longish wire on the reverse. The long wire allowed the frame to droop downward slightly to reflect the darker carpeting of the gallery. This was to prevent it from reflecting the white walls and ceiling. As far as theft goes, I also was worried about it as mine was the smallest piece in the show. At this gallery all works were insured and if it was taken I would have received the asking price minus the gallery commission.
At the Eastman House, they do the opposite for dags. They paint the ceiling black and put wedges under the dags to angle them up.
Lighting is an issue. The old dags were polished for window lighting i.e. final polishing lines horizontal. This is why sometimes they look quite poor (hazy) in museums that light them with overhead spots. Most modern dag practitioners seem to polish for overhead lighting i.e. final polishing lines vertical. This would appear to be the best option as most gallery and potential purchaser lighting is ceiling based spot lighting