For flooring, ask Lowes about Smartcore, unaffected by moisture, and Home Depot about Allure. I believe I would lay down a moisture barrier first. I would insulate the heck out of it. It keeps it cool in summer and warm in winter. I would put the windows on the east, west and south for the best light and cross air. I would have a full wall of storage, and then again, storage around the windows too. The more, the better. Make yourself a design wall area and a quilt hanging area, a closet type for hanging up those that are waiting to be quilted. I am in the same boat you are, but I am hoping to move into a much bigger house in the next year. My sewing area is going to be large, large.