for question #1.
The color trend now for wall color, as what I have seen here abroad, are earth tones, mostly browns and greens. If you like brown as a living room wall color, there are different shades of it, some are with grey undertones, from taupe to rich dark chocolate color. Maybe you can choose something in between. If you choose this color, your sofa will stand out since its light colored, and the curtains will blend in.
for question #2
Yes, you can make an accent wall. You might also consider putting wallpaper on one part of the dining room for accent. Or you might want to try wall decals.
For question #3
Red is already a strong color, so you might like to consider the color of your cabinetry and counter top.
I like overall clean look of a kitchen given this color, so i might just opt for oak colored cabinets, darker counter tops, and glass mosaic back splash tiles of the same color family to add harmony. If not for glass, there is also porcelain, but I would choose the bigger tiles so there is less visible grout lines.