tamaltree, There are a few types of wood that don't take paint well. Heavy oily woods, like teak are the kind I mean. Most other kinds of wood will, so long as it is dry, clean and has a slightly rough surface for the paint to adhere to. If you are not a professional or an advanced amateur, don't try for the lacquer. It is toxic and highly flammable. Is that the information you were after?

With the monsoon rains I cannot imagine much will protect you from the buckets of water! I have found a solution that is a permanent structure where you can twist open and close louvers so you can allow sunshine in, but lock it to block out rain. It also seems to have incorporated gutters - I am sure something like this can be found in India (or imported from China?) http://www.louvretecusa.com/ProductRange/Opening-Roof-Systems.html

your staircase block is nice. use natural store cladding, if cost permits, else some nice stone designed tiles should also do the trick. as per the tile/stone, you can either go with the similar family for the rest of the wall painting. ensure the moldings/projections are painted in lighter tone than the walls, so that they do subtly stand out.

Veenita, Ideally you should share a floor plan and pics to get an informed suggestion. However, should you need to access those ducts once in a while you should opt for grid ceiling . It comes in a wide variety of materials now. Thànks Nitin Cornerstone Designs Bangalore.