I think you should stay with a simple pattern for draperies. Possibly a pattern incorporating the white trim and warm yellow walls. This would be soft and understated and something that you wouldn't get tired of easily. Other colors could be introduced with accessories.

Installing curtain rods at the ceiling is a great way to add height to a space, but the drapes will cost a bit more because they will have to be longer. You might get a better picture quality if you installed a projection screen over one of the windows which could be raised out of the way when not in use.

The drapes don't necessarily have to be "matchy-matchy" with the wall but they should compliment one another. If you are concerned with the drapes looking outdated overtime or if you choose to change you paint colour in the future then I would suggest getting some neutral earth tones. Depending on the style you're looking for (ex. linen, silks, sheers, modern vs. traditional, etc.)

A combination of Offwhite, Beige Upholstery and dark shades of wood would look good. Provided you keep the wood minimal . The floor can also be a similar shade of wood . Remember whatever you do, make it look rich and elegant, only then will you be able to pull this look off. I am assuming the your ceiling is considerably high as well. Paint the walls and ceiling in offwhite shades with only the feature wall grey