Here's standing inside the boys bedroom looking out into the living room through the giant hole that I'm creating. Its pretty amazing how much work was actually involved in "making a hole in a wall".
Making an opening that big required cutting out some wall studs. After I supported the wall properly, I cut the studs out and then framed in a double 2x8 header that you see at the top of the photo. This header is supported on each side by 2 - 2x4 studs and carries the weight from the studs above that were cut off. You can also see a gas line and electric wire in the wall there that I had to relocate.
Here is a side view after the wall was completely removed, I also had to remove 2' off the side wall in the bedroom to maintain my proper clearance from the fireplace. On the floor I'm starting to frame out the platform the fireplace will be sitting on. You can also see the floor where I patched it up. Where the hammer is laying used to be the opening the brick chimney ran through down into the basement.
My dad and brother helped move the fireplace into position and I began installing the chimney pipe from there, the pieces just twist-lock together and about every 5 feet I install a wall clamp. I still need to build a hearth out in front of the fireplace and also frame in the walls around the fireplace with metal studs.