My drawing room front Window is going to be of around four feet wide. As the width of this room front wall is 10 feet out of which 3'6" will be kept for front entrance door. I am confused whether the sill height of the window should be 6 inches or 3 feet high as sofa is coming in front of it as my drawing room size is 10'0" * 14'0".

First of all the images you posted you cant make anything out what you got there. Secondly you should contact a local Architect when doing something like this, not only for structural reasons, but window design as well. He will layout window detail based on the window sizes available from a certain manufacturer or you can take his drawings which indicate opening detail to a place who sells windows, and they have catalogs of window combinations and sizes to make it work with what you have.

Narayana, With openable grills with French Windows are good ! They look good and provide better sunlight/wind into the house. The by side of French Windows are internal placement of furniture becomes an issue at times. Outside sounds and weather also affect the inside a bit more. Thanks, Nitin Cornerstone Designs, Bangalore.

Sheer Blinds are a good option. Put some plants outside if possible that will lend greenery to the inside too. Above is an image from one of my projects.