1. Yes, I have a HDTV
2. The TV has all of the available built-in tuners
3. I have no plans to buy a separate tuner. The built in one is not great, but it is good enough for both analog and digital OTA. I do not have cable, so I do not use the QAM tuner.
4. I don't plan to purchase one
5. Mainly, I'd want good digital OTA signal tuning performance and a decent price, silent, not too large, etc. Standard coax out is fine for video, though I'd consider HDMI if it was not expensive. For Audio, either digital optical or digital coax is fine. As far as I know both have enough bandwidth for all OTA audio broadcasts.