Well I'll try to make a 3d of the room and upload it. But that will take some time. Thank you :)

I have some suggestions if you are thinking budget friendly changes. Make a photo gallery with different size frames and arrange them parallel to the stairs, so you can enjoy each photo as you climb up. And for the area that will be on a level with your upper floor, try some pretty decal that will connect the photo gallery to upper level. And last, if you have budget add some beautiful hanging lights in the stairwell. Also think about repositioning your refrigerator.

Hello Vinayak, wpc sheet with acrylic laminate will cost you the same as natural stone like green marble of common shade granite. The second option is more sturdy then the first one .

normally tiles are not all geometrically perfect. the edges are often chipped or curving. that's the reason most designers use spacers and grout. but the margin of error is 1 to 2 mm. anything more than that and you can ask for a replacement.