Likely. Or at least "it is some improvement, hopefully, if calibrated carefully". Whether the lower bits in this computation mean anything is really anybodies guess.
No, not likely, definitely. I use this myself, and it sounds quite good (depends on the source, of course). Quality ranges from 'an improvement' to almost CD quality (really). Depends on the music (and playback rate, and method of down sampling if any).
If you want high-quality audio, I would suggest a real audio card
If I want to use a sound card, I'll use my peecee.