28-1 is 3-1.........this has to do with "virtual channels", the actual channel, and the channel remapping in the STB. I dont know for sure if the channel remapping for the virtual channels is supplied by the broadcaster or is coming through D* for now. When everything works like it should, the broadcasters transmit the channel remapping info along with program guide data.
Right now the 2 stiations that are multicasting ABC and CBS, the -2 sub channels have no remap info, so they dont go back to 24-2 or 3-2, although they are the same thing.
Yes the sound of the ATSC channels will be lower, this is due to the DD compression.
HD Video is the alsolute best in PQ right now. That is why live shots of the oscars for examlpe look so good. Another example is HDNet, which is mainly shot on HD Video.
While film based sources look good when telecined to HD, they often carry the "graininess" of the original film stock. Most movies are on film.
Although I dont know this pertains to ATSC, but NTSC PQ was much better with a live feed than a taped one. I dont know if this will affect HD, because HD video is capable of 1920x1080p, I dont know if any thing right now will surpass that.