I think an orb chandelier in brushed nickel would be lovely and I would definitely move the table over and you should be able to add a narrow console on that wall. You could also place the two chairs on either end of the table and use a bench to give more space. I would also take advantage of the wall where your small table is by adding an armoire (go antique/second hand hunting and refinish/paint!) and it will take a ton of storage. Your idea of adding a table behind the couch is also a good one also and you could probably afford to move the couch into the living room a bit more and definitely center it to the rug, away from the fireplace. Really depends on the type of storage you need, but these 3 options are all good.

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I agree with you about avoiding a swagged light if you can. Centering the table under the light and with the french doors is more visually appealing and you have plenty of space to add a storage console behind the sofa. Adding the console there not only adds storage, but it gives you something interesting to look at instead of the back of the sofa. In regards to the mixing metals - you can absolutely do that! A brushed nickel orb light would be beautiful, but bronze would work equally well. Mixing metals is a great way to get a more layered feeling in a space and keeps it from feeling too matchy. I recommend sticking with just two metals and the bronze and nickel would play well off of each other.

Your fireplace is pretty awesome, and it seems like you are doing well with the space already. I agree that a sofa table/console behind the couch would be lovely. It's also a great place to put a cup of coffee in the mornings. It seems like you are going for a beachy modern look which is great. I would replace the rug underneath the dining table with something more modern that matches your theme with warm grey/bits of red to match your flooring. You have a blue vase on the mantel, and you could carry the blue in little hints around the house. Adding some family photos/art to the wall behind the dining table would make the space a little more lively. Thankfully you have such an amazing space already, all you have to do is spruce it up.

Will it matter that a hanging light over the table will cut the visual line of the ceiling beam from the other room? For instance, imagine that you're standing by the entertainment center and facing the dining space--the hanging light would be seen from under the line of the ceiling beam.