Note: Installing a floor can be difficult if there's a fireplace in the living room. In this case, a floor has to be custom fit.
Right next to a fireplace there could be some in-floor heating wires that stick up from the subfloor and a curved hearth of the fireplace to contend with (Image 1).
Mark the underside of the board where the wires hit and put tape on top of the board to show where to make the cut (Image 2).
Using a dado blade on the table saw, cut some of the thickness away. The other trick is to make a number of shallow passes, so be sure to raise the blade about an 1/8" for each pass. Hold the square edge of the board against the guide and push with even pressure. If the cut is wider than the dado blade, make additional passes. Lay the dadoed strip of wood over the wires and connect. Be sure to avoid the wires when nailing the hardwood.
To cut the boards to fit the arc of the brick, double the height of the cork and then lay in another board up to the cork. When you get the space fit in as close as possible, take a small scrap of flooring, hold it against the cork and hold a marker on the inside edge. Slide the board around the arc and cork and all the boards are now marked to cut (You're using the cork as a guide to scribe).
Cut the boards using a band saw because it's easier to cut curved cuts. When using a band saw, set the guide as close to the work as possible. This will prevent the blade from flexing and binding. Work slowly and maintain blade speed.
Slide the boards back in place and they should fit the arc perfectly.