Hi Ritesh,
As for the sunshine in your workflow; in SU you can adjust the sun easily to your needs in real time and see how the shadows "come in" through the window. Now when using su2kt exporter, the scene should preserve your light settings and keep it at that time of the day (you may need to adjust the location though in the sun and sky setup in KT).
In this case I'd make sure to turn soft shadows on in KT to achieve a nicer effect.
As for bumps and all like that, I think you'll find more answers at the KT Forums where they specifically discuss such things. Anyway, when you have a decent bump map, you can apply it in the image slot of the bump map in the material editor (top right corner). This will however need some experimenting and there are not too many good materials that come with good bump maps so sooner or later you will need to go into some PS-ing as well (or something similar).
