Dear Client,
It was a pleasure for me to work on your project and wish I gain your satisfaction.

Kitchen: The best place for kitchen is at the end of the hall. one can come down from staircase and go to kitchen and vice versa, without disturbing the guests in living room. I suggest to use an double sliding door between the dining area and kitchen to avoid transferring any smell to the living areas. the advantage of double sliding door is that it can be opened just for peninsula to pass the foods or to enter as well.

Staircase: I believe you can keep the railing after a re-paint, but the stones of steps need to be changed to a wooden or another stone material which fit the floor finishing. ( same wood color than the handrail/ or a white/beige stone or Beige carpet cover).
You can also turn it into glass panel with wooden hand rail which i recommend and the steps can be done as above mentioned.

Staircase Wall: There is nothing better than having the family pictures on the wall staircase. the wall between toilet and the staircase can be filled with a table decorated with your choice of flower and pictures/ objects which are important for you and you want to see them daily before going out or you want them to show off to the guests.

Fireplace: The material I suggest is as of cement-ish block look. it can be done with plaster cover given cement pattern and different shades of gray, So the whole thing will feel like a natural stone in middle of the house.

the entrance: since it is pretty narrow at the entrance I proposed the 30 cm deep shoe and coat hanger. so in long term you wont have problem with passing from that point and you wont feel trapped. but if you wan you can change to 40cm too.
I did not have preference on how much space you need to store shoes and coat. if you need less space you can remove the closest closet to the entrance. but if you need more i suggest not to continue it until kitchen door please.
Please use mirror in the wardrobes so the corridor space feels bigger.

Furniture:

Furniture proposed here may just be similar to the real ones, since i did not have access to the real 3d models. ( the Sofa must be darker brown) .
But here i tried to offer and composition. hope you find it pleasurable and can be inspired when buying them.