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

Depends on what effect overall you want -- hot tropical feel (oranges and reds) or a bit more toned down? You can take inspiration from pictures of gardens with lime green heuchera or sweet potato -- often paired with chocolatey purple, silvery greens and blues.

Hello Sir, I do not understand- what do you mean by "changing the wall Designs." For coloring/wall papers/textured painting it is better to have finished wall. For wall cladding/tiling it is OK to have a non finished wall as well as they require a rough surface. For changing the tiles, its quite a messy, and wasteful expense. Rather, you can give the tiles of your choice to builder to install on the first go itself. Some builders don't allow such requests but others would happily do so. Some others may even offer a discount for not using their tiles. Same thing with paint as well you can give your colors to them to paint if you are not happy with white. Thanks, Nitin CORNERSTONE DESIGNS Bangalore.

morning glory is the shade that will have a beam of lightness when sunlight enters the house and the most common mistake some people do is just play off white blunt to all the walls, but I suggest u add a colour of Prussian blue or crimson red with the morning glory. hope it helps. thank you, do review us.