Well it depends on your wall color as well . since you have such concrete looking floor I would recommend you can chose any electic color like lemon , orange , yellow to give a bright look and uplift room mood or chose any pastle color of your choice for subtle feel . :)

You could put a photograph framed or as a photograph wallpaper behind the sofa or the television. Dahuez offers a range of photographs from Photographers in india & internationally duly signed by them. Big plus that it's affordable. Check www.facebook.com/dahuez

put wardrobe in L shape and mirror with small dressingg unit in opposite wall of wardrobe and plz do remove the gate and try to put sliding doors with translucent glass that make more space

You have to hire a pro for this brother. Elevation requires time and effort. before that if you could bring the washroom door in the bedroom align with the other door and adjacent to the window you will be able to use your washroom in a better fashion. Best of luck