Yes, the windows can be a problem. We put a very think and low profile stainless steel lip and used it as a "bumper" just to keep things from falling behind - that being said if something is large enough or pushed hard / far enough anything can fall down there. So you have to be careful. We attached the lip to the back side of the stone.

I love the wood counter top, but is that sustainable in a working kitchen? Does it have to have a bar finish on top of it?

This particular wood counter top is more used as a dining area... the client's are not using it for cooking / food prep. A wood countertop can be very suitable in a working kitchen - but is dependent on many things (overall look, client's care and upkeep). This countertop was made custom for the space by a woodworker in New Hampshire.

Brooks Custom Countertops make very nice tops for working kitchens and can answer more of your questions. http://www.brookscustom.com/kitchen-countertops.php

Hope that helps!
Emily Pinney