x2 what Dytecture said, this is not enough to go on. Most important thing before you do anything, is you need to know lot restrictions in that area and what are the zoning requirements, i.e. side, rear,front, set-backs. In addition the size of your house will also depend on the total percentage of a lot that can be covered by impervious surfaces (structures, decks, and surfaces likes asphalt or concrete driveways etc, which reduce natural infiltration, etc and after you obtain that information, only then you can contact a local Architect and you can roughly come up with the size of your house and layout on the lot... until that, the information you get here it will be useless to you in your case and a waste of time for everyone else. With that said, 40x104 is not a confirming lot for most of the area around here and you will need variances because confirming lot sizes usually start at 50x100, unless you in a section where ordinances permit residential cluster development. Good luck.

You've got a great space here, and there's so much you can do with it! Do you know what style you're looking to achieve? If you've already got a red and white colour scheme going in your kitchen, you can always opt for this in the living room. Sometimes grey can make the room look a little dark, so it's always worth investing in a white base, and build from there. Maybe change the colour of the curtains to something a little lighter and richer?

By adding a mirrored wall you will double everything on its view , are you ready for the look of doubles ? Plus I think that not many people would appreciate looking at themselves in a full size mirror while setting down for dinner . If the answer is yes then go ahead ,but I would work with the space and use a smaller mirror instead .

This is your plot size. Give the directorial drawing for the roads and the main entry as per the North direction