Re Q1, if a CD has scratches then a better player might compensate better (I have CDs that play nicely on my DVD player but have problems in my $40 boom box). But even a used $5 CD-ROM reader on your computer will get the same digital info from a clean disk as a $800 Denon. The difference in analog output quality will of course vary, and you probably could get as animated a discussion on the merits of D/As as you might on a discussion of solid state vs tube amps. I think my $90 DVD player provides adequate CD sound for my $1500 total cost sound system.
However, real, practical differences exist between DVD players for CDs and CD players.
1. It's easier to find DVD players, single & multi disk
2. DVD players tend to be cheaper. Nobody sells dirt cheap CD players any more
3. You can get a DVD player at Costco, Wal-mart etc., but probably not a CD player
4. DVD players nowadays require you to use on-screen menus for lots of functions, but CD players will have everything on the front panel. That means that if you're just listening to CDs and you want to select "repeat play", you may need to attach a TV to your DVD to figure out how to get to that menu! I chose my DVD changer (a Panasonic) because it had a repeat play button on the front, and that's not typical.
5. A DVD player may not have a counter on the front panel, but a CD player probably will
If money and space were irrelevant (I use the DVD for home theatre too) I'd prefer a CD player for sure.
--Martin
