Sorry, can't comment on moving the pipe - you'll need to get a couple of quotes from local plumbers for that. There are numerous discussions on this site as to cleaning chimney bricks, and nothing seems to work that well. Don't wet them, as the soot will spread into the bricks. A wire brush is the normal method, but sandpaper (?) seems to work well, but if you want a pristine fireplace, you'll need to source new bricks. As to the arch, it looks as though it needs a serious overhaul, and I can guarantee that you'll get fed up with the metal bar in the end, so maybe think about getting a brickie in to do it.