[Stereocraig]

200' sounds like a long distance, even w/ a booster.
Make sure your run is dedicated to the antenna, only.

A chimney mount may give you problems as far as moisture, birds seeking heat, creosote and/ or wind load loosening the mortar joints. Especially w/ something of that size.
If I weren't able to have towers, I would mount a tripod on the roof and reinforce it w/ strips of 2X4 on the underside.

All you need for audio, is to run your audio signal from the TV, or converter into one of your audio inputs. No need to convert to HDMI, cause it just converts back to an audio signal, anyway. Or, you could get a TV, or converter that has HDMI outs.