1. The MacBook will play CD's through its slot drive (also how you would rip them). I would say you'll have to put up with a bit of whirring noise in that case (not as quiet as your average CD player but I'd venture to guess not that annoying to most unless you listen to a lot of quiet music). Not sure why you'd choose playing the CD over ripping it and playing the content off of iTunes in that case.
2.Can't answer the question about DCD's, but the digital input on a DAC definitely does not decode a digital video signal. There is a device called MacTV that you should look into for those kinds of purposes, though I don't know specifically if it will do what you're asking. Video content takes up a huge amount of space on a hard drive.
3. It depends on the compression scheme you use. Generally, as a WAV file the average audio CD takes up around 600mb of space (110 cd's on your 80gig drive). In apple lossless a CD will take up about half that amount of space so you can practically double the number of CD's the drive would hold. I would definitely buy a drive that you can expand on if you get new CD's.
2.Can't answer the question about DCD's, but the digital input on a DAC definitely does not decode a digital video signal. There is a device called MacTV that you should look into for those kinds of purposes, though I don't know specifically if it will do what you're asking. Video content takes up a huge amount of space on a hard drive.
3. It depends on the compression scheme you use. Generally, as a WAV file the average audio CD takes up around 600mb of space (110 cd's on your 80gig drive). In apple lossless a CD will take up about half that amount of space so you can practically double the number of CD's the drive would hold. I would definitely buy a drive that you can expand on if you get new CD's.