I love the clean, uncluttered look of your home and you've made some great furniture choices. My first thought, though, is that I would try to rework the sofa/sectional placement. It really is unwelcoming looking to me to have the back where it is facing a wall, when it could be oriented to look into the room and out the windows. It seems like if it were placed in the corner under the stairs that it would feel open and invite you to come in and sit. I'd hate to be cooking in the kitchen and have the family or guests with their backs to me. If you are having a TV in another room close by, do you need one in that room, too? If, so placing a 70" unit will probably only work as you have it. But, to me, it's not going to look like a living room but more like a movie theater, which is fine if that's what you're going for. It seems like it won't be a cozy conversation area, though. I might actually flip the rooms and put the dining room where you have the sofa now. I was looking at lights used with dining rooms and ghost chairs and saw this, maybe would work in the living room? Kind of fun. don't know if it would look as good without the colored walls though. And I thought something like these were interesting to consider for over your table:

Are you saying light comes from the north until late in the day, or are you saying there is a window facing north and a window facing west.? The reason I ask is that light that enters from a north-facing window is bluer and lacks intensity. Subtle color is washed out to gray. The Inchyra Blue is very dark, looking more charcoal with a green tone to me. I would choose the Cooks Blue. Here is a comparison I put together of those two colors with some blues from your rug.While the actual colors may be off due to how color can vary from monitor to monitor Cooks Blue is brighter and won't fade as much in northern light. Also, having a brighter blue on the walls should bring out the blue in your rug. The only way to know how it looks in your room is to buy a sample and paint a board as you did for other colors. Keep in mind that the color temperature of light bulbs you use will also affect the colors of your walls and furnishings. Color Temperature is expressed as Kelvin but is not a measure of heat. Warm-white bulbs have a color temp of 2700K which is kind to skin tones but gives a yellow light. Daylight bulbs have color temperature of 5000K to 6500K, but are harsh to skin tones and emit a blue-white light. Both CFL and LED bulbs come in various color temperatures. I recommend you choose bulbs with color temperature between 3500K and 4500K for a more neutral result. HERE is a photo of how different K-value lighting affects the appearance of color. You might have to visit a lighting store or light bulb specialty store to find neutral white bulbs. As to ceiling colors, people seldom look up. Unless your light fixtures are dramatic or the ceiling color is distinct I doubt anyone will notice if two adjacent rooms have different ceiling colors as long as there is a Framed Passageway between them.

Please clarify this statement... "I like more war, colors like the beige or light tan to coordinate with each other." Also it is hard to recommend colors without some idea of the space and how the rooms relate to each other. Do you have a floor plan, sketch or pictures that you can post to help us give you ideas? Whole house open concept or 3 separate rooms with doors or clearly defined separations for different colors of paint. Also what color & type of flooring, furniture, cabinets, rugs, art etc... Without any of the above I can say I like the following colors & you might start your paint journey with:

Sounds like a fireplace re-do might be a longer-term fix. In the meantime, I'd paint the mantle a dark brown, a similar colour to your end tables. It's not trim and shouldn't be white. It pops out too much in the white colour. Another idea that doesn't involve any ripping-out is to go right over the existing mantle using a mantle slipcover in wood. Here's one of many how-to's on the internet. If you stained your brick as well, you could have a whole new look. https://www.fwmadebycarli.com/2011/01/making-of-slip-covered-mantel.html