Hello Nitin, There is not great all pre-fabricated stair I can recommend. The best thing is to find a stair builder that can make something to fit your needs. We do high end interior and some exterior work. We make our stairs in Seattle, and can then ship them anywhere. If you don't want to work with a company from far away, For USA and some international stair builders I recommend going to www.stairways.org and finding a SMA member in your area who can help. Good luck, and if you want to go with us, you find more info at www.NKwoodworking.com

http://www.blocklayer.com/stairs/stairseng.aspx This site does a pretty good job of helping work through stair rise/run for a standard or spiral stair case.

You really don't have the floor space for a stairway on that plan, even a spiral. If possible, try to squeeze out some space next to the entry door to avoid having it in the middle of the plan. It might not cost a lot of additional money to have the stairway as a bump-out along with the front door.

Any ideas to alter these old type of long windows to make it little interesting.