1. Although not necessary to just play a DVDA, a video screen is necessary to access other features, and at least temporarily for setup. No big deal though. I went out and bought a 13" TV for less than $80, and it is part of my equipment rack, just used for setup. I have no big screen in my audio system. I listen to music.
I am happy for you that you found a solution you can live with. I hope you can agree that the solution you found may not be appropriate for everyone. The fact that nearly all players on the market require a TV for one or more aspects of DVD-Audio playback is not an advantage or a plus for the format.
2. What's wrong with a downmix from multichannel? How do you think that all stereo (and 5.1) programs are produced from multitrack (24 channel) masters.
They are not even remotely the same thing. Creating stereo and/or multichannel tracks is an endeavor intended to create an original work of art. A downmix is an electronic process performed on those tracks by the player. It is a modification of the original data stream.
Some people think downmixes sound just fine. I have done A-B comparisons and found that downmixes are inferior to dedicated 2ch tracks.

