1x1-Base-Moulding. This is a very practical yet unique-feeling way to trim your walls. It's about as close as you're going to get to no moulding at all. Your walls have to be well-finished nearly down to the floor, though, which can be tough if you're changing out flooring.
Pink foam board from Home Depot, cut to fit around fireplace. I duck taped it together (underneath as well). Then, I covered it with quilt batting (folded to form layers). Lastly, I got some cheap fabric from hobby lobby and hot glued it underneath.