I would put console behind the table and mirror over it. Move the bench to other side of table. What does the other chair look like? Ceiling height makes no difference, you are going to hang mirror at eye level.

You and your stuff live in the lower 8' of the space so decorate there. Hang the mirror with center point 5' above the floor. If you put a piece of furniture under it the furniture should be 25% wider than the mirror, and the mirror's bottom frame should be 5" above the furniture top. Allow 24" to pull the chairs out and sit down without hitting any furniture or walls. You also want 18-24" behind the pulled out chairs so someone can walk behind the diners if they are being served food by a host/hostess.

I would beg you to get two more matching chairs and move or return the bench. It isn't fun to sit for a couple of hours with no back support. Try it!

I agree pcmom, benches are for little kids in the kitchen not in a formal dining room. But if they have one, might as well put it the correct position.

And then the guests will be given the chairs, and the hosts can sit all evening at the bench....