Either you make all your footage progressive or interlaced.
If you use interlaced all footage has to have the same field already in the timeline otherwise you will have the dvd not playing correctly. The export has to be in the same field as the timeline.
I still do not like Premiere’s scaling down hdv to sd but 4.2 is definitely better than 4.0 or 4.1.
Did you turn on Maximum Render Quality in the export settings?
Another way is to select clip in the project window then go to Clip/Audio Options/BreakOut To Mono. This wil give you a seperate left and right channel.