I'd put down an area rug in front of the fireplace with two sofas facing each and a coffee table in between -- conversation area for guest. Front space would be a great place for chaise or two small club chairs with a table and lamp between for reading. Lastly, the dining room table should go under the light fixture and anchor the space. So maybe, look at the space as three separate areas which might help you figure out furniture placement. Looks like a lovely home!!

I have french doors at the end of my dining room, and no matter what the color of the drapes, they are going to look like a big blob when closed. You might consider mixing the drapes with patterned or textured blinds, in which case you could open the drapes most of the time, particularly when you were in there. Or if you are handy, sew a patterned panel into the bottom of the drapes. But no matter how you slice it, closed long drapes are a big blob of something on a wall. If it were me, I'd spend the money on blinds for the windows and mix them with the current drapes. Another option I considered for privacy was fake or real stained glass inserts.

A good design rule is to leave 3 ft all the way around the table for circulation and chair space. That would make your largest allowable table size to be 5ft x 6ft.

The ceiling color or the color of your existing molding.