So many grays turn blue. after much trial and error for bdrm, bath and water closet , i'm happy with Benjamin Moore Horizon and Behr ultra in Burnished Clay. Neither look great on the card but they dry to a soft neutral gray. worth getting samples to try.

If you want to highlight the staircase wall then your could use earthy colours such as a yellow ochre! The wall could be enhanced even more by using suitable frames and making a good collage composition for all the photos that you have (I can see many lying on the dining table). This colour would match well with wooden furnitures

You should contact a staircase contractor to provide info and pricing for this cantilever stair design. http://www.caliperstudio.com/fabrication/project-types/stairs/stone-cantilever-stair

I've seen a lot of photos and I have come to realise that I really like the pastel/muted color pallete and have also come to know that they are good for small rooms. I really liked nickel grey and silver grey. Do both of these colors also belong to pastel color pallete? I am not able to find a separate section for pastel color pallete on asian paints' website. So it's difficult to find similar colors. Thanks for helping me.