Well for windows and doors you'd use gloss or satin finish paint in white and it shouldn't really be different to your white wall paint in colour , if you used the same shade of white from the same company.

Hello there, The slate claddings needs wall washer illumination. Please do that first. Place a wooden block above washing machine and cover it with wooden slats. This will double up as an iron board and a curio desk as well. Coming to the basin it is best to put a half pedestal over the niche and install a vanity mirror with storage for daily essentials. Regards, Aurum Ideas and Spaces Bhubaneswar

Aman, there are thousands of colors and atleast hundreds which will go well with natural cob light. You may have to narrow down the broad spectrum to your liking.

well narrated, however, if you can add a photograph too ... it would have been more helpful to provide a suggestion